I guess you are the enetrprising individual trader I made mention of. Nice work.Their algorithms will analyse market depth information and volume at the bid/ask (delta), amongst other things, in some sort of black box.
Additionally, I'm sure there are enterprising individual traders who have written their own code to analyse Bid/Ask data in real-time. I always toyed with the idea but never got around to it.
Quote from e-miNY:
Get quotes for the Osaka mini Nikkei if you are intrested in trading the Nikkei. That market is much more liquid.