Regular expression tool for JS.
Use the tool here http://coltpini.github.com/regexpert/
I wanted to build a JS app for regex testing. This works well. It is still in progress. But I am happy. Most other apps that I have seen have been built in other languages and didn't truely reflect the JS regex. This is in JS for JS so you don't have those problems.
The output shows the matches, there is highlighting in the block text, and a .test() result on the right side.
There is also a lookup table if you want it.