I've compiled a few websites I really like:
Fashion to Figure
And then of course the usuals: F21, Torrid, Marshall's, Target, H&M, etc., etc., etc. And of course I'm a huge fan of thrifting (what fashionable, creative college student isn't?) which I actually plan to do some of this weekend.
Gabi Gregg, who is perhaps one of my favorite bloggers, says it best: "I shop at straight size stores and find things that I can wear, regardless of whether it fits the way the designer intended it. When you're fat and stylish you have to be creative. Though the options are definitely getting better, I still refuse to limit myself to what's readily available for plus sizes because I'm not satisfied... I still bring my fat ass into H&M, TopShop, and wherever else I want. They may not make clothes to fit me, but they can't stop me from making their clothes fit me."
This is such a good philosophy to have: if you like something, can afford it and want it, get it. Don't be afraid of "being able to" pull it off. Make it work.