Hi,
this is my first posted mc map :) And sorry for my English, i am from Slovak...
Its a lottery machine for events (servers). You can choose one from 5 prizes, but random item from group is dropped. In this, you can win ANY mob head, sword, enchanted book, horse armor and music dics.

How it works?
It uses ACtennisACs redstone sequencer. It counts next line every time when button is pressed. You can watch it HERE. Output from counter going to RS lamps and dispensers. Button to prize control pistons that block the circuit to dispensers. When you press it, piston push the block -> activate the circuit and dispenser flush out item. It random, because dispensers select radom items. You can push into dispensers your own items, also don´t forgot get it in item frames inside.

I record video of this, but it in slovak. I working on English titles, so you can (later) watch it in english too:)

I hope you enjoyed this, if you like it give me diamond :)
My video (yet is it in slovak) : http://youtu.be/Ym534srYmfc
Don´t forget to resupply win prize after use!!!!

Additional Notes

VIDEO IN SLOVAK, BUT I WORKING ON ENGLISH TITLES!!!!