I recently purchased the Jugs Soft-Toss Machine. It does a lot more than just soft-toss.
What I do for blocking drills is load the machine up (which is around 14 balls) and get in a sqaut position like I would in a game about 10 feet in front of the machine and about a foot to the side (on each side) so I can alternate getting in front of the ball for a more realistic feel! Because the ball is not always going to be right in front of you. The ball will hit on a short bounce like an actully pitch would. Right when it hits I drop both knees, glove down like a shield, and chin down so I can see and I work on knocking the ball down with my chest protector. It is not as realistic as a game situation, but a great way to work on form and mechanics with out bugging somebody else!!! The machine is a great investment. I have a lot more catching drills I do by myself in my garge with the machine!