I thought that this recent web2py-users thread might be of interest to this group, so here is the link to the discussion:
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mdpierro the writer of web2py has created a stock trading application using Tornado, which he speaks very highly of in the thread, and web2py along with some jquery ui sugar. The application implements an interesting way to visually view robotic trading activity. Here is the link to his latest version which requires logging in to view:
http://code.google.com/p/emte-trading/. Runs in Chrome, select the products tab to view.