From enduring poor album sales and severing ties with her record label to reportedly suffering migraine-associated vertigo and canceling her tour, Janet Jackson could not catch a break in 2008.

It all started with the February release of her predictably oversexed ninth CD, Discipline, which debuted at No. 1 on Billboard‘s Top 200, but sold only 181,000 copies — less than two-thirds of what her previous disc, 20 Y.O., sold in 2006. Discipline‘s lackluster debut confirmed the obvious: Fans are turned off by Jackson’s breathy come-ons and soft-core dirty talk. But unfortunately, she didn’t get the memo. So, rather than gracefully bowing out of the spotlight to get her career back on track, she tapped another aging sex symbol, LL Cool J, to be the opening act on her ill-advised Rock Witchu Tour. No sooner than they hit the road in September, Jackson announced her abrupt departure from Island Def Jam. Days later, she was rushed to the hospital after falling "suddenly ill" before a concert in Montreal. A multitude of postponed shows followed, prompting LL to abandon the tour not long before her camp nixed all of the remaining dates.

I have no idea what Jackson’s next move will be in the new year, but I certainly hope it doesn’t include any more lyrics like this creepy little nugget from Discipline‘s icky title track: "I misbehaved/And my punishment should fit my crime/Tie me to something/Take off all my clothes/Daddy, I want u to take ur time."

It’s time for Miss Jackson to put on some clothes and sing a new tune.

Is Britney back on top? Or has her career gone the way of Lindsay Lohan‘s? It’s hard to say. First, let’s consider the pros: Though her new CD, Circus, isn’t a revelation on par with, say, Mariah Carey‘s 2005 lifesaver, The Emancipation of Mimi, it was good enough to open at No. 1 with 505,000 copies sold; her music videos for "Womanizer" and the title track are satisfactory, much like the songs that inspired them; and she’s finally got her svelte pre-baby body back. Still, there are cons to consider as well: As an entertainer, Brit’s no longer the electrifying dancer she used to be–her lackluster moves are stiff and sluggish; during interviews, she exudes apathy and indifference while remaining curiously vague about the details of her notorious meltdown; and her messy personal life continues to overshadow her work. So, what’s the verdict? Well, she’s certainly no longer capital F fierce, but I wouldn’t call her a has-been just yet. In fact, I’m keeping hope alive that the old Brit will magically reappear when she goes on tour next year.

A diva, as defined by Beyonce, "is a female version of a hustler." And though there’s no denying B’s claim in her new single, "Diva," that she’s "been the No. 1 diva in this game for a minute," you certainly can’t knock Rihanna‘s hustle in 2008. After scoring four hit singles with 2007′s Good Girl Gone Bad, her third CD in less than two years, she re-issued the disc last summer with three sizzling bonus tracks ("Disturbia," "Take a Bow," "If I Never See Your Face Again") that quickly soared up the charts as well. Now, after honing her live act on the road with Kanye West‘s Glow in the Dark extravaganza, and more than a year after Good Girl‘s original release date, Rihanna remains on the charts with her eighth single, "Rehab," featuring Justin Timberlake, plus a cameo on T.I.‘s "Live Your Life." For a pop star who was once dismissed as being incapable of yielding more than one hit song per album, Rihanna’s newfound staying power is nothing short of remarkable–and proof that there’s room for more than one diva in this game.

When M.I.A. was forced to cancel a festival appearance last year because she couldn’t get a U.S. visa, the British-born Sri Lankan rapper vented her frustration by writing a killer song about society’s fear of immigrants. She called it "Paper Planes" and released it on her 2007 CD, Kala. Though favored by critics, the Diplo-produced, Clash-sampling single didn’t peak at No. 4 on Billboard‘s Hot 100 chart until it was featured in the Pineapple Express trailer last summer. Rapper T.I. was so taken with it that he sampled it in a track called "Swagga Like Us"–which takes its title from her original lyrics–on his latest CD, Paper Trail, and he recruited Jay-Z, Kanye West, and Lil Wayne to pay tribute with him. Countless hip-hop remixes followed, including renditions by Jim Jones and Bun B. But the most fitting homage came from filmmaker Danny Boyle, who featured M.I.A.’s breakout hit in his movie Slumdog Millionaire, an Oscar-worthy drama about an orphan’s hard-knock life in Mumbai. The icing on the cake: "Paper Planes" has earned M.I.A. a Grammy nod for Record of the Year. Now that’s what I call sweet justice.

Ten years ago, British hip-hop soul siren Estelle would’ve been Lauryn Hill‘s biggest competition. Today, she’s a rare gem–cosmopolitan, street-smart, and unapologetically outspoken. Featuring collaborations with everyone from Mark Ronson and will.i.am to Kanye West and Cee-Lo, her outstanding U.S. debut CD, Shine–the first release on John Legend‘s Homeschool Records imprint–is a galvanizing blend of hip-hop, R&B, reggae, and dancehall. Why it didn’t blow up like Hill’s 1998 classic, The Miseducation of Lauryn Hill, remains a mystery to me. But at least her single "American Boy" scored a well-deserved Song of the Year Grammy nod. That’s gotta count for something, right?

With Amy Winehouse‘s career in the toilet, 2008 was all about the search for the next big throwback soul sensation. Duffy, Adele, and Robin Thicke dropped hot retro singles, but only Raphael Saadiq released a truly cohesive and thoroughly enjoyable body of work that pays tribute to the golden era of iconic soul labels like Motown, Stax, and Hot Wax. From start to finish, the former Tony! Toni! Toné! frontman’s critically acclaimed yet commercially overlooked third studio CD, The Way I See It, is a foot-tapping, finger-snapping delight–and he’s got three Grammy nominations to prove it, including a nod for Best R&B Album. If you’re still looking for a last-minute stocking stuffer, this is it.

She kissed a girl and she liked it. I get it. But a worldwide No. 1 gimmicky pop anthem plus a pretty face and wacky style makes not a proven superstar in my book. Don’t get me wrong, I loved Katy Perry‘s red-hot breakout hit, "I Kissed a Girl," as much as the next Sapphic sister. But her second single, the aptly titled "Hot N Cold," left me–well–cold. Ditto for the rest of her lackluster debut CD, One of the Boys, which failed to offer up anything else even as remotely fun, catchy, and irresistible as "I Kissed a Girl." I keep waiting for her other songs to grow on me, but so far, that hasn’t happened. Is it too soon to dismiss her as a one-hit wonder? Methinks not.

Today kicks off my countdown of music’s biggest hits and misses of 2008. First up, I present…

Santogold: Breakthrough Artist of the Year
Santi White, the Philadelphia singer-songwriter better known as Santogold, spent years paying her dues behind the scenes of the music business. She not only penned the bulk of the lyrics on Res‘ 2001 CD, How I Do, but she also fronted an indie rock band called Stiffed before striking out on her own and reinventing herself as Santogold. With the release of her flawless eponymous solo debut album, White finally reaped the critical and commercial fruits of her labor, as tracks like "Creator," "Lights Out," and "L.E.S. Artistes" became highly sought-after by music supervisors for TV, film, and ad campaigns. Her distinctive mix of sounds–including new wave, dub, punk, and reggae–is as edgy as it is infectious. And though her CD was unjustly snubbed for a Grammy nod, it is without a doubt one of the year’s finest releases.

Of all the female rappers who are currently missing in action–including Eve, Lauryn Hill, Jean Grae, and Kid Sister–the last one I ever wanted to hear new music from is Lady Sovereign. Her lackluster debut CD, 2006′s Public Warning, proved that even hip-hop champs like Jay-Z, who signed the cheeky British MC to Def Jam in 2005, pick losers sometimes. But despite failing to breakthrough in America, the Sporty Spice look-alike is back with a wack new Autotune-enhanced club single called "I Got You Dancing" from her upcoming follow-up disc, Jigsaw, due out next year. On Monday, she posted the video for the song on her MySpace page. There are zombies with green faces dressed as Native American stereotypes, plus shirtless dancers prancing around in football shoulder injury pads while wielding spiked baseball bats. It’s like watching a bad acid trip on steroids. Watch the madness for yourself, but don’t say I didn’t warn you.

Lady Sovereign – I Got You Dancing

Last week, I interviewed the RZA about the legacy of his late friend and mentor, Isaac Hayes, who died of a stroke at age 65 in Memphis on Aug 10. In addition to paying homage to Hayes’ remarkable career and vast body of work, the Wu-Tang Clan rapper/producer also shared with me one of his most cherished personal memories of the soul music icon: "When my mother passed away in 2000, I asked Isaac if he could he come to the funeral and do anything for me, just something to help uplift my family’s spirits. So he came to the funeral and he played ‘Never Can Say Goodbye’ on the piano. That really bonded our friendship. He’d seen me getting weak because, first of all, I was sad about the oppression of the world, and I was sad because I lost somebody dear to me. I was very popular at the time and kind of iconic in hip-hop, but I was kind of getting weak. And so he said to me, ‘Get up, man! Get the jelly out your spine, the cobwebs out your mind.’ He gave me those words that only a friend can say to you in a way that you get it and do something about it. And I did do something about it–the following year, I became a composer."