It looks like Roy Osherove has released the souce code of The Regulator.

I've used The Regulator to help me create a few regular expressions. I have some sort of mental blog on regex I think. Every time I read how to do it, I "get it" until I have to use it. Then I'm stuck.

Anyway, here's a couple of good articles from Roy explaining regular expressions. If I remember correctly, this was before he even wrote The Regulator.

And for good measure, here's a Regex tutorial on Code Project.