YSlow!
I've been playing recently with YSlow! from Yahoo! and it's quite cool. It's a plug-in for Firefox that works in combination with Firebug that gives you pointers as to why your site isn't as fast as it could be. I noticed that one site that I'm developing at the moment was rated C, so thought I'd see what I could do easily to improve it. These are the items that I sorted out. Configure ETags… continue reading.