Anybody else friggin love this stuff?
I can link to a few tools.
Metroid
Metroid (This is the better editor)
Metroid II
Metroid 3 (You'll want to look especially into SMILE. That's the main course in Super Metroid hacking))
Metroid Fusion, Zero Mission
If you need help, post here or google.
I'll get a few of my own up when I'm not too lazy.