Great targets

I like cheeze balls stuck on spaghetti sticks. Easy to set up and super cheap. Best of all; no clean up neccessary - birds do it for me. It can be quite a challenge too. You have to hit them fairly square to knock them off the spaghetti strand. Next time I set them up I'm going to coat them with powdered carpenter's chalk to see what happens. 
 
I like ice cubes as well, but I make mini-popsicles by putting popsicle sticks in an ice tray (I use a piece of cardboard with slits in it to keep the sticks straight up). Then I hang them by the sticks with paper clamps on a horizontal rod. Great explosions and they spin a little as well. Now, I need to try the paintballs, sugar cubes, chalk and valentine hearts.