favorite game development tools

I have looked at some of the tools available for indie game developers, and I am trying to find the best match for starting game development. I have done some simple game demos with Flash, but I am kind of curious about where to go next.

I am curious to know about what kind of game development tools people have used for developing their games on Manifesto, do you have any favorite game development tool?

Most serious game development is still done in C++. However, some things people have used successfully include:

Shockwave
Dark Basic

and for games of particular types:
RPG Maker
Adventure Game Studio

For the dev that doesn't want to spend any money on tools...

There's the PopCap Games Framework. It's free, intended to help devs in the indie and casual games market. It works with MS Visual C++ 2005 Express (also free!). Free registration is required and you do not have to publish through PopCap. Go here for more info.

The source is heavily commented, and is essentially the documentation as well. You need to know C++.