If you have run out of ideas about what you actually want to visualize visit DataZoo.
DataZoo is a repository for datasets freely available to the public. It is maintained by the community by tagging links to datasets with the keyword datazoo at Delicious.com. Links get loaded exclusively from Delicious.com and are ordered by date of creation.
The main purpose of this initiative is to provide designers and developers with a broad selection of open data for visualizations, mash-ups and applications.

Help adding relevant datasets to the zoo by tagging your links accordingly.

www.datazoo.artillery.ch

found via www.datavisualization.ch