Here's a nice simple infield drill. This drill covers all of the throws an infielder will make, and it is so quick paced that the players enjoy it.
Position a player at each base and home, give the catcher the ball. The players make three throws around the horn, then on the third catch, that player throws across the diamond to the player diagonally across to him. After four repetitions of this, the players run to the next base and start again.
Here's how it works:
C-3b-2b-1b-across to 3b
3b-2b-1b-c-across to 2b
2b-1b-c-3b-across to 1b
1b-c-3b-2b-across to c who makes a sweep tag.
Players than run to the next base: c-3b, 3b-2b, 2b-1b, 1b-c.
Repeat this four times until the original catcher is back at home plate.
Whenever a player throws to the wrong person, stop and give the ball back to him so he can get it to the correct player. Emphasis is on good, accurate, properly thrown balls, proper catching technique, and quick feet.