IMO if you're in the computer field, you can expect to make $15-20 an hour working for a decent sized company as an intern.
However, don't forget that if you're interning away from school, you'll probably be paying more for rent, utilities, etc, then you're used to. (or maybe not, depends) I have heard of undergrads making as much as $24/hr (but that is rare) and some companies will even through in benefits like subsidized housing, transportation, etc. But don't count on it - and I'm guessing the changes the computer industry is going through will likely end a lot of those frills. I was happy as an intern making ~16 an hour, which is usually more than fair for the work you're expected to do and the other benefits you receive.
More important than the money - having one or two internships under your belt will go a long way towards impressing future "real" employers. It will also get your foot in the door if you want to pursue a career at the company you intern with.