I can't think of anything off the top of my head, but I CAN think of the opposite-- I never played the campaign modes in Halo and Halo 2, just (tons and tons of) multiplayer. Halo 3 is the first game in the series I played in campaign mode, mainly because of the online co-op with 2-3 other people. I also played more of Splinter Cell Pandora Tomorrow and Chaos Theory in multiplayer than I did in single player mode.
EDIT- Timesplitters 2 and 3. Could never get my friends to play multiplayer with me, they always wanted to play Halo instead.