There have been four Special Editions of the Xbox to date. In the order of their release, they were:
1) Launch Party Edition: Clear Jewel with Bill Gates' signiture in it.
2) Japanese Special Edition: Translucent grey (smoke) case that came with two translucent grey controllers (S) and a special keychain with Bill Gates' signature engraved on it.
3) Panzer Dragoon Orta Xbox: Only released in Japan. It is white with some PZO art on it and comes with a matching white controller, a copy of PZO, and a special PZO pendant.
4) European Special Edition: Translucent Green. Don;t really know what it comes with yet.