New variants on the advance fee fraud hitting Craig's List
The more recent variant involves someone who advertises a nice place to rent on Craig's List and then absconds with the deposit. Read more about it at An Unread Blog.
In general, take the Craig's List warnings about dealing with strangers very seriously.
Related scams: You're looking for a roommate, and the interested party sends too big a deposit. The blog Active Rain has a good analysis involving a college student looking for a roommate, and a scammer willing to take the student's college fund.
Wikipedia has a good compendium of advance fee frauds.