For our baseball skills and drills workouts we like this round-the-horn drill. It works ball-handling, concentration, and conditioning.

Round the Horn Drill
5 players occupy 1B, 2B, SS, 3B, and C. Extra players line up behind SS.
The drill starts with the ball being hit to SS.
SS throws to 1B, then jogs to 1B.
1B throws to 2B, then jogs to 2B.
2B throws to 3B, then jogs to 3B.
3B throws to C, then jogs to C.
C the ball to coach (batter), then jogs outside third baseline around to the end of the line behind SS.

Variation: Once the players get good at it, start a second ball halfway through the rotation.