Console-specific development wikis
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 (Sega Genesis/Mega Drive and add-ons)
Archaic Pixels (PC Engine/TurboGrafx-16, add-ons, and PC-FX)
MSX Assembly (MSX)
SMS Power (Sega Master System, SG-1000, SC-3000, SF-7000. Game Gear)
Saturn documentation (Sega Saturn)
PS2DEV Archive (PlayStation 2)
GC-Forever (GameCube)
Free60 Archive (Xbox 360)
PS3 Developer Wiki (PlayStation 3)
Wiibrew (Wii)
WiiUbrew (Wii U)
xboxdevwiki (Xbox)
Handhelds
GBdev (Game Boy/Game Boy Color)
PlanetVB Wiki (Virtual Boy)
GBAdev (Game Boy Advance) (not really a wiki, but it was the best resource I could find)
DS Wiki Archive (Nintendo DS)
NDSTech Archive (Nintendo DS)
3Dbrew (Nintendo 3DS)