The conversion rate in that picture is very, very off.
This looks awesome provided we can get the conversion rate correct / spread down to a reasonable amount.
The site quotes conversions as a function of the pricing and volume of the markets involved. The price the site offers is basically a function of whatever price you could get by placing a series of market orders to fulfill the quantity you wish to purchase. So in a low liquidity market, the conversion price can go up rapidly for larger quantity orders as orders close to the market feed price get consumed. In the case in question above, there's apparently not any offers to sell BitBTC close to the market feed price (I checked with my wallet's exchange display to confirm this was the case).
To avoid this, we just need more people willing to act as market makers. There's a number operating now for some assets, and I suspect we'll see more in the near future (if necessary, we'll setup some of our own). We're already planning to run market makers for the UIA IOUs we sell (e.g. TRADE.BTC which we back with BTC), so if we see any other assets like BitBTC that we offer that no one else is market making, it may make sense for us to step in and fill the gap.