i think the internet should be exclusively devoted to this subject.
a year or so ago i found out that most of the great apes can inter-breed and produce viable and sometimes fertile offspring. being a normal guy i immediately wondered, does that include us? was lovecraft right? if people could cross-breed with apes, then you can be damn sure there would be a buncha ape-men running around out there.
according to a number of blogs and one or two moderately reputable sources, the russians have already tried to do this:
http://news.scotsman.com/international.cfm?id=2434192005
more importantly, someone has already tried to file a patent for humanzees, and there is at least one discussion group of animal-rights activists who want to interbreed chimps and humans in order to further their cause, in much the same way that people bomb abortion clinics to further the cause of life.