some nice ideas there
I believe a Lotter Item is in the process of being made by feildmaster
What issues were you having with the prediction game, or have you moved on?
buySignature sounds like a great idea for an item.
It would be fairly simple to make.
Would you like to attempt in making it? I can give any advice or answer questions that you may need or have.
I would probably recommend, just a form with a textarea. On post, and a few parses, update the users signature field in the members table