Metroid.com

Metroid.com is the official site for the Metroid games. It currently holds links to the Metroid Prime, Metroid Prime 2: Echoes, Metroid Prime 3: Corruption sites. Curiously, the Metroid Zero Mission and Metroid Fusion are still up.

Metroid.jp
Metroid.jp is the official Japanese site for all the games mentioned above.