Create a directory of all apps built on top of the Data.gov data. Allow voting up/down, ratings, etc. so it becomes the iPhone App Store of civic software.

If the catalog of all Data.gov data were machine readable people could build great indexing + search sites. RSS feed or otherwise.

e.g., A search for "Bird" should return datasets that mention both "Bird" and "Birds"

Each data source on data.gov needs a discussion forum and a way for the community to vote on the priorities for improving the data source (like UserVoice). Make the commentary on using the data be open source, contributed by the users.

Many researchers need data sets for dissertations and thesis work. Market data.gov directly to those most likely to use it.

Ensure that data.gov iitself s transparent. Expose the suggestions for data sources that people want, and let others vote and comment on it. Display how long it takes from making a request to getting it up on the site.

Instead of having to use Google Maps. Let 3rd parties add their own to a built-in list that users can select from.