Forum Moderators: phranque
Decide what sort of projects you're interested in working on.
If you're thinking of selling to clients (especially small businesses) yourself, they will want to see examples that are VERY directly similar. Clients (myself included!) don't have much imagination. =) But seriously, non-technical people won't have an ability to judge what's "easy" or "hard" so they'd rather see that you can do exactly what they want. If you're not a design-y person yourself, you may even want to team up with a designer for your portfolio (and potentially for your actual work, in case the client doesn't have their own designer).
A brochure site for one of your school clubs, maybe with a forum and a mailing list, might be good.
If you decide to go for outsourced tasks from technical people, then go for examples that will show your technical brilliance ... but I'm afraid I can't really give any guidance on what that would be.
Best of luck to you!