Posterous; Paused. Possibly Permanently?
I've never run or hosted my own search engine. I've run and hosted web servers, mail servers, proxy servers and caching servers (I'm even contemplating running my own URL shortener), but never a search engine. There was a time when I ran an enterprise instance of Alta Vista back when I coded for a living and was part of the team building Factiva.com, but that doesn't count.
If I had have run my own search engine I would have known just how important canonical URLs are and that having multiple copies of the same content hosted on different domains would cause search engines to penalise you and loose search engine ranking, fast.