I've raved about the Web Developer Extensions for Firefox on more than one occasion. They're the single most useful
tool I have for testing web sites, and one of the things that makes my web development experience today far better than
it was a few years ago.
If you're a Safari user, you may have felt left out—a common feeling, since Safari is woefully undersupported by many
of the latest web apps. Now there's Safari WebDevAdditions by
Les Nie, which will attempt to bring some of these features to Safari. The current version is an "early beta release
only" but already supports some of the key features—outlining tables and other elements, and disabling images. I'm sure
many more features are on the way.
WebDevAdditions is a SIMBL plug-in and requires SIMBL.
