Redstone/noteblock mine timer.

Another older development of mine. Developed, but unfortunately never used, on a server where you were able to buy multiple complete (sky limit to bedrock) chunks of land. The server was shut down before I got a chance to fully implement it. It's set up for servers utilizing some from of editable land protection (such as allowing other players to destroy blocks in your area if given the proper flag), an economy system (such as iConomy, BOSEconomy), as well as some from of door/chest/furnace protection (such as Lockette)
My concept:Sell "miner passes" a pass good for "X" amount of uses (In my case 10) for "X" amount of Currency (In my case 8000). Miner passes would be normally unobtainable items such as: Fire, Double stone slabs, Water, Cobwebs, Ice, Sponges, Portal, and locked chests.If you didn't want to buy a miner pass, each entrance cost 1000.
The system works off of a 5-minute timer activated by a pressure plate.
The timer used is MrFinnJohnson's - http://www.youtube.com/watch?v=2nlfeDVAKpA Mining duration can be increased or decreased in 5-minute intervals by coupling multiple timer systems together.
Once the last timer system pressure plate de-pressurizes, it activates a note block in the main "reception" area notifying the "teller" to notify whoever is in the mine that their time is up, revoke their flag, or teleport them out.