It looks like a couple of hundred fed-up freelancers have decided to air their grievances about sloppy paying by their clients (or should I say "clients"?). It stops short of naming and shaming, although there's a bit at the bottom where clients can be rated.
http://www.worldslongestinvoice.com/
I should say that I have had very few problems with being paid (although some clients are quicker than others ...), but I do know plenty of freelancers and self-employed folk who've had to deal with tricksters who've tried schemes such as claiming the work was substandard (but using it anyway).