+1 Don't bother trying to beef up the frame.

I had a Firenze MT505 mountain bike that I used as a commuter for my first year in college. It wasn't a bad bike for $10. The components sucked but it held up to a lot of abuse. I even crashed it into a building and bent the top tube and downtube pretty bad. Still rode it the rest of the year.

I've thought about getting another as a novelty.