I realise this article on drug trials and what can go wrong is an oldie.. BUT I just returned from Melbourne where they are happily advertising on Nova Radio (by the way a fun and generally good station!) that healthy young people who are not on any medication can be paid for taking part in drug trials - to assess the way certain drugs are processed in the body.
There was not one mention of the fact that these trials may harm you and even in some circumstances, may be life threatening.
Check out the link re the drug trials that went horribly wrong in the UK this year.. in fact 6 healthy men all under 40 suffered multiple organ failure, and two were said to be critically ill.
So this is a warning to the unwary. Even if you are broke and this appears to be a good way to make some cash.. think again. Don't donate your body to science before you are dead! Science is not always on the right track.