Split a ball on a axe blade to hit a card on each side at once.
Tac a balloon by the tail then shoot over the shoulder with a mirror. (More fun on a breezy day)
Small block hanging from a string, cut the string.
Under the table with hand gun at a close target with out being able to see the gun.
Shoot a plastic bucket at a unknown range. The ball must enter the bucket and stay there so you have to guess the charge to get in and not go threw or knock the bucket over.
These are some I’ve shot and enjoyed at various places.
I operate Woodswalk at Friendship, and am always looking for new and innovative target ideas to put in action. My comments on Phil's suggestions are:
Split a ball on an axe more frequently is scored by shooting clay birds with the ball fragments. The results is instantly seen, although cost and cleanup are greater.
Small block hanging from a string. I use a golf ball for weight to hold the string taut. The target frame is up a small slope, so ideally the string is cut and the ball rolls down the hill to you.
Set up a board and partially drive a shiny nail with a big head on it into the board. If your rifle is a real tack driver, you'll drive the nail into or through the board with your ball.
I'm partial to a stake shoot, where a 2x4 or similar is set up for each team (maybe 4 or so on a team, and everyone shoots at their stake until 1 team cuts theirs in two with their shots.
Depending on where you live, in the Fall you can shoot at hedge apples (Osage Oranges). They tend to really jump high when hit