Thumbtacks stuck in the top of a board. Put up two rows of 10 tacks each, whoever makes them all disappear first wins.
The 4"-6" solid rubber bouncey balls. Set it on the ground and 50yds and compete with your range partner to "bounce" them to whatever your desired range is.
Hockey pucks. Drill a hole 3/4" from the edge, tie a string and hang at 300yds.
Drive 10-penny nails through a piece of plywood.
Make your spent shotgun shell hulls bounce around, works real well after the ground is good and iced up in the winter, the hulls bounce around real good on the ice. If you're good with your semi-auto .22lr, you can make the hulls bounce up in the air a foot or two, then hit them again while in the air.
Fill an old pop bottle up with water (use food coloring if you like) and put the cap back on. Lay the bottle on it's side with the cap facing 90* to your barrel direction. Shoot the cap off and empty the bottle.
Small party baloons. To make it more visual, put a teaspoon of baby powder in the baloons before you blow them up and set them out on the range.
Cheap old chain (thin links). Shoot the links off one by one with a .22lr.
Dum-dum suckers, staple the sucker sticks to a board and shoot the sucker part with a .22.
Old baby carrots, any old produce that's trashcan bound really.
That's all I can think of at the moment.