http://dcode.io/ *
First 2 minutes, I click click click a bunch and smile a bunch and it was all very cool. (dropdown at the bottom has a RIDIC # of named patterns -- "superstring" is FANTASTIC.)
After 2 minutes, I have to stop myself from looking "under the hood" to see how quickly I can get the gist of how this baby works.
I have a sickness, don't I...
* found via https://github.com/MadMG where I was looking at the "moment.js" Date/Time framework (http://momentjs.com/), also way cool (a bit less visually engaging though ;) )
Hah!