Choice of Chart
A few years ago Dr. Andrew Abela published a good Diagram helping to decide about which chart are a better fit for a given data and problem at hand (please click on image below to see it in full size).
Good people at Juice Analytics converted Dr. Abela’s diagram to online Chart Chooser application, I suggest to review it. You may also review this post here and presentation from the same author, available online: Which chart? or as full screen slideshow: http://www.slideshare.net/slideshow/embed_code/3707753