Absolutely. The way you get the immediate feedback on what is being matched is extremely helpful. Thank *you*!
I don't know if this is the place for it, but I was thinking it would be even better (feeping creaturism, here we go) if you could have a list of strings to be matched. So instead of entering just one, you could enter N strings, maybe 1 per line, and watch the regexp match them at the same time.