Ask HN: Where can I find test data?

Hello Friends,

I'm doing some work comparing various data storage engines. I'd love to get a large dataset or two to use for the comparison. What do folks here use for large amounts of test data? The domain doesn't matter so much.

I've previously looked at the US Census data and that qualifies for the "large" part, but it's a little unstructured. It'd be cool to get some CSV files that are easily loaded into a variety of tools.