This article has a nice list of tools for data visualization:

http://www.netmagazine.com/features/top-20-data-visualisation-tools

and the person I've follow the most is Edward Tufte, http://www.edwardtufte.com/tufte/[/url]

i enjoy his moderated forum: http://www.edwardtufte.com/bboard/q-and-a?topic_id=1