Data.gov should have a crawling program to identify data agencies make available (usually as CSVs) & use a standard page listing the field names. Commonly accessed data should have more in depth description of fields provided by the corresponding agency.
Widgets for blogs & other personal pages should be made to allow easy utilization of the data for casual or non-technical individuals. Simple functions could include line graphs, pie charts and YoY chart comparisons. More complex tools could join data from multiple sources such as budget numbers correlated with office incumbent time periods.
The Bureau of Economic Analysis has a decent example in their "locking stubs" graphing feature. Choose a table to see what I'm talking about.
Google has an API with the kind of visualization features I'm referring to. Providing an online form to generate graphing code for a page/blog would be a big step.