This spring look out for plastic bag collection sites on campus and in dorms. We've found a place in the city who collects used plastic bags and recycles them, which is far better than sending them to landfills. So if you've got a stash of plastic bags that you swore you'd reuse but never did, fear not, soon they can be recycled.
In the meantime, get yourself a tote bag, available at JJ's and most local grocery stores, so you never have to use a plastic--or equally bad paper--bag for your shopping. Seriously, get a reusable tote bag and use it. Now.