1.Dr.Mario - NES
2.Super Mario World -SNES
3.Bubble Bobble - NES
4.Sonic the Hedgehog 2 - GEN
5.Guitar Hero I & II - PS2
6.Rock n' Roll Racers - SNES
7.Marvel vs. Capcom II/Street Fighter II - DC/SNES
8.Earthworm Jim - SNES
9.Worms: Armaggedon - PS
10.Diablo II - PC

This list isn't accurate, but these are the games that popped in my mind right away when I thought about games that I play over and over again, year after year.

01) Deus Ex (PC) - This has to be my true n.1, since I play it through atleast twice every year.
02) Civilization IV (PC)
03) Fahrenheit (PC)
04) Jones In the Fast Lane (PC)
05) Super Mario World (SNES)
06) Star Wars Battlefront II (PC)
07) AvP 2 (PC)
08) Gold Rush (PC)
09) Rock n Roll Racing (SNES)
10) C&C Generals (PC)
*Not neccesserily in that order!

Nice. Another Rock n' Roll Racer.

mario kart 64
tetris
Zelda OoT
counter strike source
super smash bros melee
goldeneye
perfect dark
wii sports
solitaire

Goldeneye
Starseige: Tribes
Unreal Tournament
Mike Tyson's Punch Out
Ninja Gaiden NES
Duke Nukeem
Astyanx
Super Mario Bros 3
Ken Griffey Jr Baseball N64
Mision Impossible N64 (lol bit of a wierd for some but I quite enjoy this game)

Ultimate Block Party (PSP)

http://psp.ign.com/articles/678/678154p1.html

Zoo Keeper (NDS)

http://ds.ign.com/objects/707/707319.html

Sim City 3000 (PC)

http://pc.ign.com/objects/014/014520.html

Sangokushi 2 (Arcade Game)

http://boneash.oldgame.tw/MAME/mame-1-52.html

Evolution Soccer (Winning Eleven)
http://www.gamespot.com/ps2/sports/worldsoccerwinningeleven10/index.html?tag=result;title;7

Depends on the genre and the definition of "replayable."

For example, a fighting game where each new battle counts as a replay will always be higher than an RPG where a replay means many hours of play.

A better question would be along the lines of "What games have you spent the most time playing?"

As I stated above, I didn't like that particular question because games like FF are going to take way longer than games like ICO if we based it on time playing.  Someone would have to play ICO 15 times to match the playing time of a Final Fantasy.  Yet, I would think that playing through ICO should be on that person's list.

 I figured people would use their own internal reason to mix the two thoughs (time playing and times played) to make their own list.  Given the responses, it looks like everyone has.

Super Mario Bros 3 (beaten at least 30 times)
Super Metroid & Prime (each beaten almost yearly)
Resistance (Me and my buds tear up online & co-op all the time)
Way of the Samurai (played through it probably 8-10 times but that's the nature of it)
Shenmue I & II (just keep coming back til 3 comes out... right?)
GTAs and Bully (beat all 5 3D GTAs and Bully at least twice apiece)
Shadow of Colossus (Most mind-blowing game ever - must've went back and played the thirteenth colossus over fifty times)
Oblivion (Countless hours)
Monster Hunter (Countless hours)
FF Tactics
TMNT1, Monster Party, and Star Tropics on NES, personal favorites
Contra 3 and Wild Guns on SNES
Wave Race and MArio 64, and BLAST CORPS!
Klonoa, Einhander, Syphony of the Night, FF9
Too many...

Oh yeah and can't forget any and all King's Quest 1-7, I've got em all on my laptop and play them whenever the mood strikes