The premise of Powabunga is a bit difficult to explain, but once you start using it it turns out to be a very cool product.
Imagine a spin of a typical auction. Someone wants $100 for a product they're selling. Instead of trying to reach $100 as the auction price, they sell 100 auction seats for $1 each. By the time the auction has started, the seller has already collected her money.
The bidders can then bid on the product with an arbitrary currency (carrots) earned on the site by performing different tasks, or by trading the currency amongst each other.
The advantage to the seller is that she can name his price. She can even sell money.
The advantage to the buyer is that, with enough carrots, she can buy something very expensive for only one dollar.
I was assigned to do several odd jobs on the site including some promotional videos and artwork for the home page. The hardest assignment was in developing a page with featured auctions, written in Java Spring MVC.
The featured auctions section would take one item every hour or so, and offer high carrot bonuses to users who entered paddles (the $1 auction seats). I was assigned to create the timer to cycle through these featured items and to create a frontend interface to greet users with the new system.