Man, my list is going to be huge I'll have to edit this later because I'm at work and don't know all my games off the top of my head but here's a start:

PC Games:
Neverwinter Nights - 40% done
Legends of Aranna - 40% done
UT 2004 - 98% done
Everquest - it never ends....
Freelancer - 75% done
Starcraft - 5% done

Xbox Games:
Beyond Good and Evil - 10% done
Dues Ex - whatever the sequel is called, about 2% done
Crimson Skies - 20% done
Knights of the Old Republic - 2% done
Splinter Cell - don't remember how far I got into this
Halo - never finished it in Legendary
Splinter Cell: Pandora Tomorrow - 15% done maybe a bit further
Ghost Recon - only beat the first two boards
Ghost Recon: Islands of Thunder - still need to unlock a few things
Rainbow Six: 3 - still want to beat it in the hardest mode
Unreal Tournament - haven't really gotten into single player story
NBA Live 2003 - haven't finished a season
ESPN Hockey - haven't finished a season
ESPN Football - haven't finished a season
Madden 2004 - haven't played it yet
Armed & Dangerous - haven't played it yet
Hunter: The Reckoning - about 40% done
DoA Extreme Beach Volleyball - don't think there is a true ending to this
Obi Wan - 20% done

Gamecube:
Metroid - about 75% - 80% done I think
Resident Evil Zero - haven't played it yet
Viewtiful Joe - haven't played it yet
Mega Man Anniversary - haven't played it yet
Eternal Darkness - 15% done
Mario Party 5 - not sure, really just started
Animal Crossing - don't think it ever ends

I'm sure there are a lot more, need to see what games I have to find out.