Bionicle: Heroes gives you at least 20 points per relatively quick level you play through -- along with plenty of 20-point bonuses. Play through 2 levels, you'll get 80 points.
King Kong gives you 100 points per level beaten. I'd say levels average an hour each.
Fight Night Round 3 gives 100 points per sponsored fight. I'd say it'd take an hour and a half to get to each of those.
I got mad points on both Amped 3 and Condemned, and actually really enjoyed my time with both.
Kameo, Tony Hawk's American Wasteland, and Gun all are liberal with the points.
To a lesser extent, Splinter Cell: Double Agent, Rainbow Six Vegas, Tony Hawk's Project 8, Marvel: Ultimate Alliance, Dead Rising, and LEGO Star Wars II all hand out some decent achievement points (200-350 pretty easily), and I'd say they're more fun than the other group above.
For Xbox Live Arcade games, oldies like Pac-Man and Galaga are good. I also recommend Uno.
If you want quick points, stay away from most racing games (except Test Drive), Quake 4 (only 160 points through beating single-player), and Sonic and Bomberman Act: Zero -- because ithey suck all-around.