Low rent for work done (http://philadelphia.craigslist.org/apa/1907794275.html - broken link)
This has to be the one for me. Lets see. You fix up this house for free and then buy the finished property after you've fixed it up! Where do I sign up
Paying to do labor? Almost as good as working for free!!
Doesn't sound like anything malicious to me but doesn't sound too well thought out either.....