This site has links to the homepages of 92 different IDS systems... http://www-rnks.informatik.tu-cottbu...birey/ids.html
And this is a really good FAQ. Way to big to post the whole thing here...
http://www.ticm.com/kb/faq/idsfaq.htmlVersion 0.8.3, March 21, 2000
This FAQ answers simple questions related to detecting
intruders who attack systems through the network, especially
how such intrusions can be detected.