A few years back (well, many years now actually)... Microsoft gave me a free copy of Visual Studio 6 Professional Edition for taking and passing a MCSD beta exam.
At the time, I was amazed because I think the software retailed for like $1000. It was like winning $1000 in a lottery - well, not exactly but still... free expensive software.
Nowdays, Microsoft offers their Visual Studio Express products free. I am using Express to assist with a big Open Source development project from home, and it's incredible that it is free. In fact, they may have lost a sale of the retail version of Visual Studio 2005 to me, because I don't need it.
Yesterday I heard that Borland is offering it's Turbo products free - Turbo C#, Turbo Delphi, Turbo C++. Wow again. So if I wasn't using Express already, I would definitely try Turbo C#.
Java people have Eclipse, which I hear is really good. Are there any other really good free development tools out there? Let me know.
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.