Recently, I've seen a few posts at places that I frequent that talk about the difficulty college students are having finding a job over the summer. To be sure, employers will be more likely to hire a person who needs to pay the mortgage and feed their kids over someone who can simply crash at home with their parents over the summer break.
One thing that college students without summer jobs should consider is writing content online. Of course, you probably know that I write at Associated Content. I am not getting rich, of course, but every little bit helps. I also do not do this full-time, mainly because I have a lot on my plate with kids running around, dishes to run through the dishwasher, blogging here, church activities, etc. If I could sit and focus on it as a full-time venture, I'd probably do all right. At least at AC, you can ask for (and sometimes receive) an upfront payment, plus there's always the page view bonus structure which sweetens the pot.
It shouldn't take more than a day or two of solid reading of the forums there (Writer's Workshop has excellent articles regarding writing online vs. writing print) and you should be off and running. Posting for help (after you have done your reading) should yield advice that is invaluable to you to improve your writing and writing in such a way that your hard work will be found by public infoseekers.
Aside from AC, there are other places that college students can write. This includes Bukisa (no upfront; page views only), Demand Studios, Break Studios, Textbroker, etc. For help in finding paid gigs, I recommend checking out the forums at Accentuate Services. There are legitimate writing opportunities out there aside from content writing sites.
One other thing that I would mention is that taking the time over the summer to get your feet wet writing content can help pad a college student's bank account later. By developing a skill over the summer, a college student can write as often as they can during the school year to help pay for college expenses (and perhaps a pizza or two). When you can't find a job, sometimes the best solution is to create a job for yourself.