One of the things I've always wanted to be able to do is create nice game creation tools. A nice syntax highlighted editor etc. So a while back I started writing something simple using Scintilla. Then at work a lot of Lua coding was required so last Sunday night, yesterday night and a bit this morning I made my own lua editor / IDE and released it open source http://code.google.com/p/monmon/ (it's still undergoing development)
I had been using UltraEdit but today might that day I can start eating my own dog food, as they say.
The editor is called MonMon it does rather a lot with very little code - check it out!