I found this while trying to decipher some user-agents in my site's logs: http://www.zytrax.com/tech/web/browser_ids.htm . Pretty useful for checking what that $_SERVER['HTTP_USER_AGENT'] really means.

Nice post !!!

What would be really cool now is if someone put together a nice little app for PHP / ASP / JSP / Client-side Javascript that would neatly categorize all of those in terms of functionality for DOM, DHTML, Layers vs. All, CSS compatibility, etc. so that developers could just plug in the code and start programming to different interfaces.

http://skrlin.com/Testing/new/userData.htm

I was messing around with something like this a while back. If someone wants to pick up where I left off and continue/re-write/optimize the code let me know and I can post all the code used.