Sweet question!
1. Legend of Zelda - Link to the Past - I wasted way too many hours on this one and still remember beating it for the first time
2. Super Metroid - I'll never get sick of pulling this one out and replaying now and then
3. Tony Hawk Pro Skater 2/3 - again, way too much of University wasted playing these
4. Counter Strike 1.6/Source - still wish i didn't suck so hard at this one
5. NHL94 - adding one-timers, so awesome!