I just found this site a couple days ago. Quandl is a new startup that is a search engine for datasets. The site really has a lot of data (over 2 million datasets). Plus the data can be sorted, filtered, graphed, combined, and finally downloaded in many different formats (Excel, JSON, R, csv, XML). Most of the data is numerical and/or time series.
If you have been looking for some data to explore, Quandl may be a good place to look.