there are also gamebase databases for AtariSt, Atari Lynx, C64 (with 30000!! screenshots and 15000 games) and for ZX Spectrum.
For nes an online database exists:
http://dod.hpi.net/ivgdb/
but im still looking for sms, gb/gbc/gba and pc-engine/tg16 databases.
Anyone know something like this?