Regex .NET
A simple free .NET tool for working with regular expressions.
After pounding my head on my keyboard trying to get a number of regular expressions to work I wanted to name this program Rejext. Regular expressions have the ability to make award winning obfuscated C code look tame but the power they provide makes it worthwhile to spend the time to learn them.
Regex won't teach you regular expressions but it will help you create regular expressions by letting you see the results of a regular expression match without having to recompile your program each time. It is very gratifing to watch the results of your search appear as you type each character in your expression. You really need to try it to get an idea of how well this works. Each time the text changes in the expression, result or input fields the results of a match will be displayed in the output window.