I use http://mtgoxlive.com/
for a more short term market depth + recent trades overview if I feel the urge to put up a few orders gefore going to bed...
I don't understand that graph. It's kind of cool, and I hadn't seen it before, but the left axis goes from 0 to 7000BTC while the right axis goes from 0 to $900k. What does it mean? For 7k BTC to be $900k we'd need bitcoins to be worth over $100 each.
Also, why does the brown line stop before hitting the edge? I'd expect there to be enough buy orders for tiny amounts to push the line off the edge of the graph.