For those who use Smultron instead of TextMate, here is a way to get the new Web Inspector into Smultron for inspecting DOM and CSS, debugging JavaScript, monitoring Network transfers, and more...

1. 1.Download a nightly build of WebKit and put it in your folder /Applications.
   

2. 2.Open Terminal.app and enter
   

3. defaults write org.smultron.Smultron \WebKitDeveloperExtras -bool true
   

3. 3.Download SmultronKit and put it anywhere you want, and then you can drag it to your dock. Launching SmultronKit will open Smultron with the nightly WebKit, and then you can right-click in the Web Preview and choose “Inspect Element”!