I have been really irritated by the number of bots crawling my site. My irritation was from two sources:
1. Useful bots are welcome - e.g. google, yahoo, etc, but most of the rest just steal content and slow your site down. I banned about 200 known bot types by blocking them at my web server. My server load when down immediately...
2. Statistics - as you all know it looks stupid if you are showing 1000 guests that aren't really guests. I wrote
this hack to deal with the problem. It's a little different to the one linked above. You should check both hacks out and decide which suits you better.