Since many of us have absolutely no idea where to find this huge intellectual effort, I decided to summarize in this post, those who are, according to my research, the 10 best websites for piano sheet music of videogames.
The research was long, but as always you will enjoy the results:
Definitely the best online resource for videogames sheets
Sheet music for piano and other instruments of the famous Monkey Island game
Spariti di Final Fantasy
Some scores of the most famous games for Nintendo and SegaMegaDrive
Many scores but not updated
Zelda, Supermario and FinalFantasy scores
Few sheets, but interesting
Well stocked website, many scores, primarily videogames for NES
Well stocked, worth a visit
Many of the most famous games
Official website of pianist creator of Final Fantasy soundtracks
Yet scores of Final Fantasy
Good download and … feel free to comment for updates, links, corrupt, or just to thank my five hours in the summer spent in front of the monitor 
