Lutz Roeder’s Reflector is the coolest .NET tool on the planet, but things in the .NET world just got a whole lot cooler: http://weblogs.asp.net/scottgu/archive/2007/10/03/releasing-the-source-code-for-the-net-framework-libraries.aspx smile_nerd

If your brain survived that onslaught, this is pretty neat too: http://weblogs.asp.net/rajbk/archive/2007/09/18/dynamic-string-based-queries-in-linq.aspx (I’m using it as a lightweight expression evaluator instead of CodeDom; has some restrictions but nothing too scary).