» Lori Firefox Extension

The Lori Firefox extension provides very valuable information when you're developing websites, as it shows time-to-first-byte, time-to-complete, the page size and the number of sub-requests used to build a page with every request. Comparing those values to some metrics (rules of thumb really) you know whether you're doing it right or not. Hmm... I'm not sure whether I want to try that on my own site ;-) (no download link for the XPI yet, probably have to wait a day or two until the author notices he forgot something)