if it's anything like a forum I admin'd a year or so ago, it's probably google/msn/other search/crawlbots.
=P
They always use the same IP #'s for the spiders from each search engine.
Google should have an account made for it hereso it can scan the things we allow it.
Other boards (The Watcher's and many privet P2P clubs) have scripts/code that prevents the spiders from even reporting they exist.