Great idea, ironhorse. Our program has used many of these drills since this thread originated (as a matter of fact validation BP is on the practice plan today) and I've love to see it take off again.
One of my favorite up tempo/competitive BP's is called "Six Outs BP". It is detailed in Andy Lopez's book Coaching Baseball Successfully and goes like this:
Set Up: Players should be divided up fairly equally into 3-4 hitting groups. They will compete against the other groups so in order for the drill to be competitive the groups need to be as equal as possible. Players not hitting should be at their defensive position and the defense should be two deep at each position (excluding pitchers and catchers). Coaches throw BP.
The Routine:
1) Each group's goal is to hit for as long as possible. The timer/stopwatch will start when the first pitch is thrown and continue until the group makes six consecutive outs. We don't make our players run the ball out (but you certainly can) - but we do use a "play" stopwatch and infielders must have the ball to first under the minimum time or the ball is considered an infield hit.
2) The outs build up until a player gets a hit and the outs reset at zero. If the group makes 6 consecutive outs the watch stops and the groups total time is recorded. The next group will then take their turn and this continues until all groups have hit.
3) We give each group an equal number of rounds to hit (usually three).
4) After 5 minutes the coach throwing BP will mix his pitches up to make it more challenging on the group hitting.
5) Any ball that hits the L screen on a line or one hop is considered a hit.
6) Some days we play the highest single round wins and on other days the winners will have the highest cumulative total.
7) Winning team gets a prize (sports drinks, gum/candy, etc.)
This BP is extremely competitive and fun for the players. You will see great effort from your defense because they want to get the hitting group out of the cage ASAP. You'll have to keep an eye on the defense to make sure the "appropriate" player makes the player (if we don't watch ours there will be six "live" outfielders!).