How does one read and interpret the data on the MtGoxLive/Orders chart?
The axes have units. The new help link at the bottom does not have much information.
It's essentially a market depth chart, with the orange/brown line on the left representing the (cumulative) volume of standing buy orders and the blue line representing the (cumulative) volume of standing sell orders. The y-axis represents an amount of BTC and the x-axis represents a given buy/sell price in USD. The green line represents recent historical price shifts in that value.
At the top right are large numbers representing the current, high and low prices for the day. From the "Help / Options" menu at the bottom right, several additional options are available including the ability to show volume as lighter or darker shades of green on the price line and the ability to disable the gray ghostlines which appear every time the volume curve shifts. This Help/Options dialog also contains the following helpful instructions:
This is a cumulative graph of the outstanding orders on the MtGox exchange. It shows how much BTC/USD will have to be bought/sold before the market rate hits a certain USD price. For example, let's say you want to know how much USD would have to be spent buying BTC before the price reaches 40 USD. First find 40.0 on the bottom axis. Then find where the blue line intersects $40.0. Now find what value that corresponds to on the right axis. If it corresponds to $200000 then that's how much USD would have to be spent buying BTC before the price reached 40 USD.
Brown and blue curves represent Market Depth. It shows how much USD or bitcoins someone would need to spend in order to move the price to a certain point on bottom axis. Green curve is past trades price.