What I'm currently planning to include is the following:
- "Prize groups" which will allow the spending of different items and currencies to get different prizes. You would be able to create several prize groups, so you could have lots of different Shop items that could be spent on the slot machine.
- Support for all Cash mod currencies, not just user_points.
- A "jackpot" feature, that allows someone to win all the cash spent on previous non-winning plays. This would be tied into the prize groups, to allow several different jackpots of you wanted.
- Four rewards per prize group. There would be one each for a match of three common, uncommon, rare, or very rare pictures. Jackpots would take the place of the very rare reward. When using Shop items, you could define several items and one would be selected randomly.
- Possibly more rewards for partial matches (2 out of three for uncommon, rare, and very rare). I'm not sure about this; I might drop the idea.