Does one need a work permit for work experience in Thailand as part of a college course? I am specifically thinking about the hotel management courses. These require a certain amount of experience in a hotel as part of graduation requirements.

Could a student come here on a tourist visa and do such unpaid work legally?

It looks like technically you do. Apparently volunteer work requires a work permit, however it might be possible that if you obtain a visa to study in Thailand that unpaid training work may be included. After reading your post I started a thread called "Thai work permits, what are they good for?", there are a few answers that are interesting if you want to have a look. But check out what the education visa permits in terms of practicums..

Good luck