We all know that Apache web server powers a majority of today's internet. An alternative lightweight open source web server, lighttpd, is fast gaining popularity specially with the Web 2.0 folks such as YouTube, wikipedia and meebo.
Bill Lubanovic of ONLamp.com has a tutorial on installing and configuring lighttpd. I recommend that you check it out and try it. It definitely will lessen the load on your server. :)
I have been using apache tomcat and lighttpd, lighttpd is great when your application logic is simple ie only servers images or videos, lighttpd will be a lot faster. but lighttpd does not have nearly as many as apache does.