Do you host your site through dreamhost? If not, you should. They’re fantastic and great.
In fact, they just got even more fantastic: http://blog.dreamhost.com/2010/11/04/mod_pagespeed-now-available/
If you already use them, you should totally go and turn this feature on. Go ahead, I’ll wait here.
To save you reading their blog post: They have enabled mod_pagespeed as an option for domain managers. This module dynamically rewrites pages before they’re served to make them faster to download and faster to render. Why is this good? Well if everyone used it, you could browse twice as many sites with pictures of puppies, kittens, or sugar gliders in the same amount of time.
Full disclaimer: This is one of the projects I work on.