VC++ 2010
A very helpful IDE and compiler, supports custom appwizards, all round, a well put together program. Nothing much else I can say.
Code::Blocks
I'm no where near as accustomed to Code::Blocks as I am with VC++, it's still a great program, and allows you to use a selection of compilers, it also detects appwizards that VC++ can't, and because it doesn't use .NET it can help with cross-platform development. I'm not as interested in this at the moment, though if, once I get going properly, you would like to try porting NewDawn to Mac or Linux, be my guest. I'd be happy to add it to the (coming soon) downloads.
Audacity
Of course, I enjoy playing around with music and clips in this program, for a while know I've been mixing tunes from Freeplaymusic for some of my own little games. It can be used for so many different things.