I have briefly detailed one of these drills,(I will send more later). However, there is one rule that I use with my catchers: They will perform every drill with chest protector & shin guards on (sometimes a mask but it can get pretty hot.) The reason for doing this is that catchers must be able to react, act and think when they are uncomfortable and sweaty. If you can get your catcher(s) to 'buy-in' to this it will make them better in the long-run. Besides then you can really see who wants to catch and who doesn't.
1) With full gear on (mask too) have your catcher get behind the plate w/out her glove. Make sure she has a balanced stance with her weight on the balls of her feet, knees bent (thighs parallel or slightly past) and toes slightly in towards the plate. Draw a circle in the dirt about the diameter of a washing machine around the plate. Have your catcher assume her crouch with both hands behind her back.
A coach/player (never a pitcher) then throws Incredible/WhiffleBalls, Tennis balls (to start with then move to regulation alls) low pitches/short hops at the catcher. Using only her chest, legs and shoulders the catcher tries to make every ball stay within the front of the circle. The catcher must use her body/shoulders to keep the balls within the cirlce by 'bowing' her shoulders to guide the balls to the front of the plate within easy reach distance.
We do this drill at 10 balls/3x for 30 balls a session with 3 sessions. We also increase the reps until 1/2 through the season and then decrease because of physical strain on the catcher(s) after 60-80 games in both school ball and summer ball.