Of the nearly infinite ways of using crossfilter and dc.js in finance, the 2 that immediately came to my mind are signal analysis in system building and money manager analysis in due diligence. My first very basic experiment explores a commonly known signal (RSI) on the daily S&P 500 since 1950. Interactivity adds a lot to the experience. I used R to grab and reshape the data and slidify to make it pretty. Check it out by clicking here or on the screenshot below.
For another very fine example of dc.js and crossfilter in use with AAII Stockpicking strategy data, see this fine site.