I hate mean girl drama! Definitely have dealt with my share as mama bear of Erin, as well.
There's no right answer, Tammie. I find that when I see a particular girl in public, and I can discreetly give her my 'mama look' that says "I'd love to knock your head right off your shoulders if I could and you know I would..." it at least makes me feel somewhat better.
But I've preached, coached, and loved Erin through understanding that the thicker her skin, the broader her shoulders and the "You aren't going to steal my joy" attitude works very well. Easier said than done. We have a pact that when she has a bad day (and they are much much less now), she is granted amnesty at home and can get it 'all off her chest' to me and I will just let her spit, say, cry, rant, rave however she needs to.
I've also tried to teach her that life is definitely going to rain on everyone in some form or fashion and it's very hard to watch those who are undeserving seem to breeze through life... however, I know this to be true, those that breeze through in high school will seldom make it on their own in the real world. Ab needs to be who she's going to be and while it may mean not receiving awards that she most definitely earned, she's definitely got her smarts and no one can take that from her. Tell her "The tallest trees are always going to catch the most wind." She's their target because they choose her to be... most likely out of insecurities and jealousy. She won't understand that right now.
I really_really like Ashley's advice about her building her rapport with her teachers. Help her find a support structure, those rare true friends, even if it's just one or two, who are going to get her back just as she will get theirs... She'll make it!! It totally sucks as a mom watching our girls hurt! Start practicing that stare I was talking about... pretty fun to watch them cower away.
One more thing... research your state laws on bullying... in Oklahoma, and it may be nationwide now, it's illegal. If she is having issues, have her document them, and if the school is not doing anything, force their ethics in because it's the law and they have a duty to protect each and every student in their school as well as provide a learning environment that each and every student can succeed in... and that includes student conflict resolution.