A month or so ago, I made a magic 8 ball. There are a number of variations on that theme to be found in SL. Mine has custom images that appear on a triangle prim that are revealed by an alpha changing window when you click on the 8 ball. My own variation if you will.
I made it for fun above any other consideration. But when it was done I stuck it into a Magic box for sale on SLexchange. Somebody bought one today. I hope they have as much fun playing with it as I did making it.