Google Correlate -- "finds search patterns which correspond with real-world trends." -- correlations of search terms of Google search users.
Public Data Explorer -- a searchable repository of public data, together with visualization tools (Google's post on this, Slate article on this). Starting in 2011, you can also upload and visualize your own datasets.
Fusion Tables -- awesome visualization tool that Google uses with Public Data, and that you can use in Google Spreadsheets.
