Artist: Aly & AJ (78violet)
Ages: Aly Michalka, 20; AJ Michalka, 18

Why They're Hot: This sister act juggles both successful music and acting careers. The duo has two studio albums under their belts, 'Into the Rush' and 'Insomniatic,' the latter of which includes their smash single 'Potential Breakup Song.' Individually, Aly Michalka and AJ Michalka boast impressive acting resumes with roles in 'Bandslam' and 'The Lovely Bones,' respectively.

What's Up Next: Aly & AJ recently changed their name to 78violet. The duo will release their third album in 2010 and it will be self-titled.