February 22, 2006 +1 more...
I was ready to live with it, when I suddenly remembered that AWStats, my favorite logfile analyzer, does a pretty good job at keeping track of robots/spiders. It actually includes a Perl module with around 400 regexp user-agent matches for all sort of known robots, spiders and crawlers.
I converted the AWStats lookup data into a Java class, Robots, which I used in my Servlet.
Thanks to Laurent Destailleur, the author of AWStats, for allowing me to release it in the public domain.