One game that I haven't seen mentioned, my Dad called "Cribbage". You break a random rack like you would for 8 ball, and if you make a ball you have to then shoot the other ball which adds to 15 (make the 7, try to get the 8). Then shoot the pairs that add to 15, saving the 15 for the last shot. Each pair made is 1 point, game is 11. Having to shoot pairs makes you play good position and plan the rack carefully, and if you miss the second ball of the pair it gets spotted as closely as possible behind the break spot. Shooter who makes the 15 gets to break.
It's an interesting game and will improve your skills and frustrate you at the same time.
It's an interesting game and will improve your skills and frustrate you at the same time.