Best co-op system link games?

[projecteightysix]

What are your favorite? I just moved in to a new apartment with my roommate and we have our x-boxes linked together now so... whats good?

 

[BREVITY]

Halo1-ODST
Borderlands
L4D? Cant recall

 

[Nealocus123]

Borderlands, without a doubt. Me and my roommate have put countless hours into this game. Probably one of my favorite of the year if not all time.