i recently found a few interesting links dealing wiht both server-side and client side caching for php pages. I thought some people who wants to help reduce server load might be interested in them.

(client-side) http://www.developertutorials.com/tu...ing/page1.html
(server-side) http://www.developertutorials.com/tu...ing/page1.html
(server-side, for people with their own servers) http://sourceforge.net/projects/eaccelerator/