Hack, Code or plugin to deal with Fake Traffic/bots

I’ve got a nasty bit of bots that have alternating IP addresses, referrers ect that keep eating away at my site’s bandwidth. I’ve used .htaccess to block some refers and ips but the attacks are so varied that it’s impossible to keep up with.

I’ve given it some thought and the only way that i can think of to stop the majority of the fake traffic is to block an IP after so many pageviews, say 7.

The typical REAL user only visits 1-4 pages so if i can block an IP automatically after 7 pageviews then re-allow after 48hrs or so, that would be ideal. Anyone know of a plugin or hack to do this?