There is this as well http://www.amazon.com/Enterprise-Dashboards-Design-Best-Prac...

The The Grammar of Graphics (Statistics and Computing) by Leland Wilkinson is also great, though more focused on building graphing systems. I believe it is the inspiration for a lot of d3.js http://www.amazon.com/The-Grammar-Graphics-Statistics-Comput...

That Stephen Few book is pretty much all you need, but you can also check out Edward Tufte's books, and Juice Analytics' white papers (http://www.juiceanalytics.com/).