Replacement for .Net Reflector
Red-Gate used to offer .Net Reflector (http://www.reflector.net/) free. It was a handy tool to help you see the contents of .Net libraries and executable. It is especially helpful if you wanted to verify whether or not your .Net compiles were obfuscated (I use Preemptive Dotfuscator) the way you intended them to be. If you got an update in the last several months though you probably discovered (some time ago?) that it was no longer going to be free. They expired their app and now it doesn't work.
Fear not, for ILSpy appears to work just as good (at least for my purposes). Go get it.