A fan made tribute game I've been watching for a while is Super Mario X for PC. Without a doubt they've packed alot of great features into this free indie game. Combining sprites from the classic mario games with some other classic Nintendo games. My favorite is the new power ups with seem to stay true to the spirit of the classic games. If you find the 50 levels inspiring Super Mario X also sports it's own level editor to go crazy with. (more...)
ExplodingRabbit over on the Newgrounds.com flash portal has released a flash based reworking of the original super mario bros. Super Mario Crossover lets you play through the nintendo classic with five new playable 8-bit game characters. Each come with their own unique movement and special attacks.
The 5 new playable characters;
Link from the Legend of Zelda
Bill R. from Contra
Mega Man from the Mega Man series
Samus from Metroid
Simon from Castlevania
Check it out