Oblivion: At one stage I had 1.5 mil+, but spent it all. No idea how much I have now.
Wallpaper gallery:
http://www.digitalblasphemy.com/dbhome.shtml
A lot of it is members only, but the free gallery is definitely worth a look.
Microsoft XNA:
http://msdn.microsoft.com/en-us/xna/default.aspx
XNA is a free toolset intended to make game programming much easier. It definitely has its good points and does make programming a bit easier, but I haven't had enough time yet to make something serious.
Games can be made for Windows (2.0 and 3.0), the Zune media player (3.0 only) and Xbox 360 (at the moment, 2.0 only).
XNA 2.0 Download: Search microsoft.com for "xna 2.0" (I have no idea if a direct URL will work)
XNA 3.0 Search microsoft.com for "xna 3.0 ctp" or simply "xna 3.0".
XNA 2.0 requires Visual Studio 2005 or Visual C# 2005 Express (free download, free to use)
XNA 3.0 requires Visual Studio 2008 or Visual C# 2008 Express (free download, free to use):
http://www.microsoft.com/express/download/ - you can also download any Visual Studio 2008 Express product there (Visual Basic, C#, C++ and Web Developer). There's also a link to download 2005 versions.
XNA might also require the most recent version of the DirectX SDK - not too sure at the moment.
XNA Creators Club:
http://creators.xna.com/ - this is where you actually download all the sample, how-tos and games themselves. Some stuff is "premium", the vast majority is free. Support & forums are also located there.
Enigma - a somewhat addictive simple to play game. Open source
http://www.nongnu.org/enigma/
It's available for Windows, Mac and many Linux versions. To quote the website itself: "Enigma is a puzzle game inspired by Oxyd on the Atari ST and Rock'n'Roll on the Amiga. The object of the game is to find uncover pairs of identically colored Oxyd stones. Simple? Yes. Easy? Certainly not! Hidden traps, vast mazes, laser beams, and, most of all, countless hairy puzzles usually block your direct way to the Oxyd stones."
The actual Diamond Caves game that part-features in RnD (in case anyone is not aware of it yet):
DC3:
http://www.diamond-pro.com/games/dc3.shtml
DC2:
http://www.diamond-pro.com/games/dc2.shtml
RnD can load DC2 levelgroups, available on the Levelgroups page.
File recovery utility for those accidentally deleted files:
http://www.undelete-plus.com/download.html
At the moment, it's free to use.
Edit: XNA 3.0 has now been released.