I just happened to look to see who all is on the site right now and I noticed that at the moment we have 3 search engine bots on the site.

exabot, googlebot, and yahoobot.

Which leads me to the question, what search engine is exabot from? I have never heard of it.

Yeah, we can't exclude the bots showing up as users since we did the forum upgrade. exabot is the bot from the Exalead site who "is a global software provider in the enterprise and Web search markets, and the maker of CloudView, the industry's top platform for Search-Based Applications (SBAs). " - taken from their site.