This is the tool any serious .NET developer must have. I should perhaps qualify it with saying Visual Studio.NET developer.

I've installed the 3.0 beta, as I spend quite a bit of my day in VB.NET now and it has better support than the 2.5 version (plus I get a free upgrade to 3.0 when its released).

It is awesome. The unit test runner is worth the price of the tool alone, and you can get the unit test runner for FREE(!!) from their website! The refactoring support is awesome. The editor enhancements are first rate.

I'm blathering now. Just go and download the trial version and see for yourself.