zelda lttp super mario world championship manager 01/02 - but with newer unofficial updates.... EDIT: oh and space quest 4 & 5
Chrono Trigger (I finish it once every winter vacation), Final Fantasy VI (I've bought it and finished it for every system it's been released on... stupid, I know), Final Fantasy IV, Axelay, Thunder Force V, Front Mission 3, Street Fighter 3, and Burnout Revenge. Also: Much of the SNES First Party lineup (Super Metroid, Pilotwings, F-Zero, Super Mario World, Yoshi's Island - to name a few). SNES was so Awesome... and it still amazes me to this day.
Doom / Doom 2, Alex Kidd in Miracle World, Killzone 2, Burnout 3: Takedown, OutRun 2006 Coast To Coast, Metal Slug, Daytona USA, ... I would also add Warhawk, Philosoma, Jumping Flash and Tekken.
Rez, Banjo Kazooie, Legend of Zelda OoT and NES, S.T.A.L.K.E.R. (gets less buggy every time I play it because of the patches), Castlevania SOTN, Conker's Bad Fur Day, Starfox 64
Most of the people here in Poland go back to Baldurs Gate II just when someone mentions it. I personally always go back to StarCraft:BroodWar. This is like 10 years since I've been playing it(ladder games). I really like to go back to snes games with FF6 on top. As for playstation - Final Fantasy VII,VIII and Tactics.
Super Metroid for sure... used to finish it twice a year, but I will admit that number has gone down. Everything about this game is perfect. Half-life 1 and 2, considering I map for these games as well as coding, texturing, modeling, etc. I am on them nonstop. Chrono Trigger of course! =] Never got to play the DS "Remake". Is the added coliseum even fun?
Kingdom hearts, final fantasy viii, donkey Kong 64, doom, goldeneye, jak and daxter, pokemon, legend of zelda ocarina of time, final fantasy x, shadow of the colossus
Forgot to mention Rock Band 2 in my first post, definitely go back to that one all the time, especially since it has the best DLC ever.
Secret of Monkey Island 1-3, Indiana Jones and the last Crusade, Indiana Jones and the fate of Atlantis, Maniac Mansion 2 Day of the tentacle, damn I love those Lucasarts point and click games.