Ruby, Rails, Firefox, Anime, Mac
The Regex Coach allows you to experiment with your regular expression (regex) and quickly determine how it would match your target string. It would be a very useful tool for trying out all any examples in any tutorials or books you may be reading. Also serves as a good testing platform for verifying your regex interactively (as opposed to writing it in your script, running it, and then checking the results). I wish I had this when I was learning regex.