Sunlight Labs recently launched their National Data Catalog, an open platform for government data sets and APIs. It makes it easy to find datasets by and about government, across all levels (federal, state, and local) and across all branches (executive, legislative, and judicial). The data here is imported from multiple sources and curated by Sunlight Labs staff. They aggregate sources from: data.gov, data.dc.gov, utah.gov, datasf.org, and the Sunlight Foundation and its partners.  The hope is to expand its reach as the federal government moves forward on its open data agenda and more local and state governments embrace the open data movement.