It is interesting that the real reason why craigslist succeeds is not mentioned. IMHO, it's because of being like a *local* classifieds, free, and without word limits. Also, the local dating, I suppose. I dont think it was unique either. In 1994, when I was a outsource programmer at a Dallas telco, there was a hugely popular newsgroup on the company intranet where people bought and sold stuff, told each other of local events, and was a kind of meeting ground. I tried to get my bosses at other places where I worked at, to do this - but the fears of legalities always killed it.