I think the best and the part that I used the most amount of time on was the economy system. It's a very good one. There are pictures on the main page about the economy system. There comes a few commands with it.
- /balance [player] - Check anyone's balance. (To check others balance, you need the permission, 'erscommands.balance.others'.
- /economy <add, remove, set, reset> <player> [amount]> - Add, remove, set or reset someones balance.
- /pay <player> <amount> - Pay a player money.