For me, my loans are at 6.8%, (Stafford), and have an extended loan as well around the same interest rate. Since I know I have extra and know I'll need money in the summer, I offset a tiny fraction of this by locking it up in a CD for 6 months. Sometimes it's kind of silly to have a credit card at 2.9% for life and student loans creeping up every year.
Anyway, I personally can't give you more info than that. 🙂