Instant Regex Evaluators on the Web

I've been using regular expressions heavily lately and it is always convenient to go to an instant regex evaluator to see if you're writing the right expression. Be aware that different languages evaluate regular expressions in their own way. So the regex that runs right on Ruby will not necessarily run the exact same way in Java.

Here are the online instant regex evaluators I've found useful:
Ruby - http://www.rubular.com/
Java - http://www.regexplanet.com/advanced/java/index.html