Here's a list of wikis dedicated to hosting documentation regarding console hardware and development. Useful for those interested in coding homebrew software.
Consoles[]
NESdev (NES)
SNES Development Wiki (Super Nintendo)
MegaDrive Development Wiki (Genesis/Mega Drive and add-ons)
Archaic Pixels (PC Engine/TurboGrafx-16, add-ons, and PC-FX)
Free60 (Xbox 360)
PS3 Developer Wiki (PlayStation 3)
Wiibrew (Wii)
Handhelds[]
GBdev (Game Boy/Game Boy Color)
GBAdev (Game Boy Advance) (not really a wiki, but it was the best resource I could find)
DS Wiki (Nintendo DS)