CritterNYC - 5:29 am on Jun 24, 2004 (gmt 0)
There are so many gems within the Web Developer toolbar.
You've played with the "View Style Information" function, right? Click CSS and then View Style Information (or click CTRL-SHIFT-S) and the pointer turns into a crosshair. Click on any element and you'll find out all the style rules applied to it. Great for trying to figure out if your rules are being applied correctly.