10) Kesha: 'TiK ToK' (2009)
Featured off her debut album 'Animal,' this iTunes single -- with auto-synth back beats -- muses about the singer's crazy night out partying. The chorus is a definite party rocker: "Don't stop, make it pop / DJ, blow my speakers up / Tonight, I'mma fight / 'Til we see the sunlight..."
9) Leona Lewis: 'Bleeding Love' (2007)
The 2006 'X-Factor' winner released this R&B/pop track as her lead single off her debut 'Spirit.' Although it is considered a love song, the song's structure is more R&B danced-based (with wood block percussion and synthesized strings) than a slow-tempo ballad. This song not only made iTunes top 10 most downloaded list, but was the best-selling single in the U.K., as well as the top selling track of 2008, according to Nielsen SoundScan.
8) Taylor Swift: 'Love Story' (2008)
She may not have perfect pitch, but she sure can write, sharing the perfect love story that every girl would want, lyrically tying in the story between Romeo & Juliet (sans the tragic ending, obviously): "Romeo, take me somewhere we can be alone / I'll be waiting, all that's left to do is run / You be the prince, and I'll be the princess / It's a love story, baby, just say, 'yes'." This tune was one of the first songs to successfully crossover from country to pop, and become not only the most-downloaded country track in history, but the best-selling country song in the U.S. -- surpassing LeAnn Rimes' 'How Do I Live?' by 1 million copies.
7) Flo Rida: 'Low' (2007)
The first single off his debut album 'Mail on Sunday' the song features T-Pain, who also co-wrote the song. According to the RIAA, this top downloaded iTunes song received the highest Gold & Platinum certification of any artist in March of 2008, earning Flo Rida Gold, Platinum, and 3x multi-Platinum prestige for his chart-topping song, which was also ranked No. 3 song on Billboard's Hot 100 Songs of the Decade.
6) Lady GaGa: 'Just Dance' (2008)
The playful tune with prominent dance beats has the glittery, swaggering-bombshell singing about being wasted in a club: "What's going on on the floor? / I love this record baby but I can't see straight anymore / Keep it cool, what's the name of this club? / I can't remember but it's alright, a-alright / Just dance." Praised by critics, the song stayed on the Billboard 100 for almost five months before it finally topped the charts in January of 2009.
5) Coldplay: 'Viva la Vida' (2008)
A band known for stadium-scale melodies, this track's melody is no different, recognized for it's repeated, punchy string section -- so much in fact that musician Joe Satriani accused Coldplay of copyright infringement, saying that the melody was copied from his 2004 'If I Could Fly.' Luckily for Coldplay, the case was settled last September, as both parties reached a financial settlement. The lyrics to the song mention Roman cavalry, Saint Peter and Jerusalem bells, adding religious references to a pop-y song, which won both Song of the Year and Best Pop Performance by a Duo or a Group at the 2009 Grammy Awards.
4) Jason Mraz: 'I'm Yours' (2008)
Even though the song was released as Mraz's first single off 2008's 'I Sing. I Dance. I Steal Things,' the track was originally included as a demo on his 2006 limited Edition 'Extra Credit,' an EP to help promote his album 'Mr. A-Z.' 'I'm Yours' was nominated for two Grammys in 2009: Best Male Pop Vocal Performance and Song of the Year, but lost to John Mayer's 'Say' and, yep, Coldplay's 'Viva la Vida,' respectively.
3) Black Eyed Peas: 'Boom Boom Pow' (2009)
This top iTunes song -- with furturistic lyrics "I'm so 3008 / you're so 2000 and late" and heavy auto-tune -- gives the band a digital rebirth, not only in their sound but their image as well. So much, that in fact, the group won a 2010 Grammy for Best Short Form Music Video.
2) Lady GaGa: 'Poker Face' (2008)
Despite its upbeat electropop vibe, the song denotes a darker meaning sex and bisexuality, metaphorically linking to gambling: "Luck and intuition play the cards with Spades to start / And after he's been hooked I'll play the one that's on his heart." GaGa says she wrote this top downloaded iTunes song as a tribute to her rock 'n' roll boyfriends. The song won a 2010 Grammy for Best Dance Recording.
1) Black Eyed Peas: 'I Gotta Feeling' (2009)
You've blasted this top 2009 song once or twice while getting ready to go out, danced along to it at a club, and even rocked out to it at a house party -- yep, just like the music video, which features cameo appearances by co-producer and French house DJ David Guetta (other producer is Will.i.am) along with Katy Perry, American rapper Kid Cudi, and model/actress Chantal Jones. This No.1 downloadable iTunes song won a 2010 Grammy for Best Pop Performance by a Duo or Group with Vocals.