Late on rent? Loan shark breathing down your neck? Can't fill your car with gas to get to work on Monday? Assuming all available funds and traditional sources of credit are tapped out, here are 25 (legal) ways to raise cash in a few days. We list them in order from least to most desperate.

Most large universities have ongoing medical research projects evaluating the efficacy of new medicines and treatments. As part of this evaluation, they often need 'volunteers' on which to test these medications. Since the pool of willing volunteers is limited, cash compensation for the volunteer's cooperation is sometimes provided, ranging from a few hundred dollars up to four figures.

Among the opportunities I found on a quick check: The University of Washington is paying $250 for participants in a study of extended stored platelet concentrates. The National Institutes of Health has 300 studies that need volunteers. Rochester Clinical Research is looking for volunteers to test an Avian Flu vaccine. Google medical test volunteers for more.

Most studies are looking for reasonably healthy people. And, of course, this could be hard-earned money. The fact that you are a guinea pig means that there is at least a slight chance that, through you, the researchers will discover negative consequences of the medicine or treatment. On the upside, you'll probably receive a free physical.

All 25 ways to raise quick cash.