Check out this list of iTunes and last.fm’s top downloaded singles of 2008. As you can see, it was quite the year for Coldplay and Rihanna, both of whom will probably figure heavily when the Grammy Award nominations are announced tonight. Every year, I predict the winners of the February award ceremony, and I generally call the winners pretty closely (which says as much for my prognostication skills as it does the Grammys’ predictability). Here are the artists and albums I think will be nominated in the three major categories.

Record of the Year: Coldplay’s Viva La Vida is the front runner here. Leona Lewis and John Mayer are probably sure things for Bleeding Love and Say (which I also think is the front runner for Song of the Year), Rihanna will probably be nominated for either Take a Bow or Disturbia. Katy Perry could snag a nod for I Kissed a Girl. I wouldn’t be surprised to see Kanye grab a nomination for Homecoming. We might see some love for Chris Brown’s With You, with outside shots for M.I.A.’s Paper Planes and Adele’s Chasing Pavements, and don’t count out Mariah Carey’s Touch My Body or Madonna’s 4 Minutes, despite the relative disappointment of their album sales.

Album of the Year: Coldplay is again the front-runner in this category, far and away. Also look for Radiohead’s In Rainbows to score a well-deserved nomination. Lil’ Wayne had the year’s biggest selling album with Tha Carter III, but Grammy generally doesn’t roll out the red carpet for hardcore rap acts. Alicia Keys is almost certain to get a nod for As I Am, while labelmate Leona Lewis could score big here, too. Dark horses here include Jack Johnson, Metallica and Carrie Underwood, and we can’t forget The Eagles’ huge-selling Long Road Out of Eden.

Best New Artist: Leona Lewis is the obvious front-runner here, but we could see love for a variety of different artists. Fellow Brit chanteuses Adele, Duffy and Estelle (whose American Boy could also see a Record of the Year nomination) could all follow in the steps of last year’s winner, Amy Winehouse. Indie faves Vampire Weekend and The Ting Tings could pop up in this category, as could Timbaland proteges OneRepublic. Also watch out for country group Lady Antebellum as well as American Idol’s Jordin Sparks and Jennifer Hudson.

We’ll do a recap of the nominations tomorrow after the announcements have been made!!