Emma Stone, after Superbad, Zombieland and now Easy A is an easy pick as long as doesn't become a Lohan type statistic. Currently being considered for the Spider-man reboot and with five films set for end of 2010 and through 2011, here's an easy pick for someone to keep your eye on over time.
A few quick notes on Emma Stone:
Easy A - opened at $17.7 million in Sept. 2010. A pretty solid opening all in all.
Dig a little further and you can see that Roberts actually dropped out of Zaxk Snyder's follow up to The Watchmen, Sucker Punch so she could make this film
Minor but noteworthy role: Ghosts of Girlfriends Past...a pretty horrible film to be honest but there are two performances in this film that make it tolerable. one is Michael Douglas' sleazy Uncle Wayne, and the second is the over-the-top dressed down and clad in braces Allison Vandermeersh played by Stone.