jstar - 2:11 am on Mar 29, 2006 (gmt 0)

You can't block by User-Agent because they can easily be faked.

I don't think it hurts to include User-Agent blocking, to weed out the low hanging fruit of theives that are too dumb to mask their Wget or whatever tool they're using to download an entire site, and keep them from stealing those 100 pages a day under your IP count method.