If you like tools like this one, here's some more. There's a lot of 'visually see' the regex type tools.
As one who always forgets regex after 3 months of not using it, I find them helpful :)
http://pineapple.io/resources/tagged/regular-expressions?sor...
I particularly find this one fascinating, even though I don't fully grasp: http://jkff.info/articles/ire/