Saints Row the 3rd is actually surprisingly good co-operatively.
Serious Sam 3 is much the same.
They aren't *great* games on their own, but the co-op element really makes them a lot more interesting.
Either can be had cheap at places like G2Play.net
Test Drive Unlimited 2 is pretty good fun Multiplay also, but not a conventional 'co-op' game.
Borderlands is pretty reasonable for a wasz with mates too...
Sorry, missed the 'one tied to a laptop' part of the OP.
Check out Co-Optimus
for the real skinny on co-op games.
Maybe some bot bashing in Star Craft, or Warcraft 2?
.If hunting for old-school FPS, Duke Nukem 3D, Blood or Shadow Warrior were also great for co-op and the lulz (tho will take some wrangling to play the game under current OS')
I don't know how many times I smashed those games way back when.