In college I donated Plasma...
If these places were better with time managment, I would have done it longer, but you can wait HOURS and an hour seemed about average... plus it can take you a while to give, depends on the person....
As degenerate as the thread title seems, if a person who likes to gamble, doesn't really have the money too, which I guarantee theres a lot more of these people than we thing... seems like a good idea for a tradeoff, get couple hundred a month