One of my favorite things about Rubular is the "Make Permalink" feature. Paste the link as a comment above your regex and you can easily get back to the same place later.<p>The permalink includes your test string(s) and makes it really easy to see what was going on when you wrote it.
Yeah this has been around for ages, not sure why this got reposted. Either way, this is still by far the best regexp site out on the net right now. There just isn't a better way to test your regexps.
I've been using rubular since it's inception. There are lots of sites/apps for building regex's, but rubular has always been my goto guy. To the developer, thanks for an awesome site!