Welcome to WebmasterWorld Guest from 220.127.116.11
Mozilla/5.0 (Twiceler-0.9 http://www.cuil.com/twiceler/robot.html)
-- and with no UA at all (scroll down to see differently-named servers). Usually Twiceler visits a few times a day. Never, ever like this:
And these were without any UA at all. At leat they did read/heed robots.txt --
Such behavior can happen in search engines when they are cleaning up a large list of URLs to eliminate those that have been disallowed. As this process is likely to be done in parallel it can manifest itself as described above.
Combined with Lord Majestic's speculation above and the "ramp" hosts with no UA, it wouldn't surprise me if they're preparing to roll out a new index some time soon.
Do any of you ever get any traffic from them? I don't.
Lord Majestic's speculation is a possibility. The last I heard of Cuil was that it was trying some social search engine experiments and some Twitter stuff was being integrated.