Shit, my bills would be paid and I'd be sending my husband to Germany for the summer to immerse himself in the language. It'll help with his 2nd major: German.
If I HAD to invest it, I'd go looking for the best mutual funds in terms of track record. Get a GOOD financial advisor to help with this, and diversify among slow growth/low risk, medium growth/risk, high yield/high risk funds. That should start you out nicely, and the interst from them can be re-invested every year to help your porfolio grow, thus earning you more money for the long-term.
