There are two apache modules that you can use to serve compressed content. Mod_negotiation is part of the standard apache distribution and allows you to configure your server to
serve pre-compressed content to browsers that support compression. Mod_negotiation has a lot of nifty features to play with.
http://httpd.apache.org/docs/mod/mod_negotiation.html
Mod_gzip is simplier to set up but less flexible than mod_negotiation. It compresses the content on the fly
which makes it a bit more convienent.
http://www.remotecommunications.com/apache/mod_gzip/