I recently came across an interesting searchable database of information graphics built by the Parsons Institute for Information Mapping. The database contains over 1200 examples of information visualization images. Their stated goal is to build the most comprehensive, manually annotated (and taxonomically classified) information graphics database in the world.
Here a few sample images taken from the results of the search for graph:
One weakness I noticed was that some of the images in the search results didn't appear for some reason. Also, they mention that they are developing a taxonomy for information graphics. It would be an excellent addition to the site if you could browse the graphics based on their taxonomy.
For me at least, it's a stimulating experience to just browse the results of random queries. On the whole I find it to be an excellent resource and I suspect I'll be returning there frequently.