Since he's a Mite, I'd recommend you get Francois Allaire's book, "Hocky Goaltending for Young Players." It's got a lot of great on- and off-ice drills, and is geared especially toward the "under-12 crowd."

It's important to set-aside some time to focus on specific goalie drills, but it's also equally important to run drills with the rest of the team...especially the defensemen.

Practice various situation drills between the goalie and his D's...1-1, 2-1, etc. Who's got responsibility for what? For example, on a 2-1, most goalies would rather face the guy with the puck and have the D take the open attacker. Also, if the goalie yells "Screen", then the D's need to know what to do: move bodies! These drills will make sure that both D's and goalies are clear as to what their respective responsibilities are, and then PRACTICE, PRACTICE, PRACTICE until their responses to these situations become automatic.