You would not believe me. Up until now I have had extreme difficulties with regular expressions, I found this while googling some tutorials for use of regular expressions in C#. Funny enough this came up. Anyway combining tutorials with this, regular expressions make a lot more sense to me and are easier to work with.
I found this nifty site, it lets you input your own regular expression, your own string to match it, then you can test it. As I was easily able to visually experiment, made so much more sense to me. And while the main function of the site is for ruby, it can be useful for other languages to.
http://www.rubular.com/Other sites just like this!
http://rise4fun.com/Rex (Provided by Zeriab)
http://www.rubyxp.com/ (Provided by mcgluszak)