Heres an article that helped me with an issue over at a friends site http://www.ftatalk.com
Their site was exploding and they need to tune out the current server as much as possible. One thing that I noticed was that MySQL wasn't tuned properly. So After making some changes and finding out that there was no thread caching, I searched the web and found this article.

Wow, it's been a busy week. I was totally swamped for several days dealing with the remember.yahoo.com MySQL servers and related stuff. And then I used a day or two to recover (sleep, shower, etc).
Anyway, I made some interesting discoveries along the way. The most surprising one had to do with thread caching on Linux when you have a busy MySQL server--busy in a particular way, mind you.

Read the full article at jeremy.zawodny.com

***UPDATE*** I have moved ftatalk.com over to lighttpd and its doing wonders! You can also check out the ftatalk.com mirror at http://www.satfix.net
I will also be writing an article about lighttpd and how it can help you get the most out of your hardware.