These are cut’n’pasted from my Coursera Computaional Investing class forum. Not yet examined, just here to follow up on.

I don’t know what Prof. Tucker chose for his company but highstock (http://www.highcharts.com/stock/demo/) is in my opinion the best around (free for non commercial products). In any case here is a list of other good visualization libraries:

http://g.raphaeljs.com/
http://www.jqplot.com/
http://plugins.jquery.com/project/gchart
http://vis.stanford.edu/protovis/
http://polymaps.org/
http://code.google.com/p/flot/