As someone who believes strongly in "Open Standards, Open Data, Open Source" philosophies, I was incredibly frustrated to hear that budget cuts are likely to cause the shutdown of a group of US federal government websites related to transparency, financial oversight/accountability, and public data sharing. The Sunlight Foundation's Daniel Schuman has written a great initial blog post about this, which was later followed up by a very thorough analysis from Alex Howard on GovFresh.
I am and have been a huge supporter of Data.gov, the primary public portal for accessing freely available, cataloged US government data. At the time of this writing, data.gov hosts almost 380,000 cataloged datasets supplied by over 170 US government agencies and departments. Over 1,000 web-based applications for analysis and visualization are available on the site, a full quarter of which have been developed and contributed by citizens in the data.gov user community. Specialized sub-portals on the site connect community members with shared interests, such as K-12 educators, public health professionals, and application developers. Topical resource collections provide data and information about timely issues - today's highlighted links include the RadNet radiation incident monitoring system and a feed of earthquakes recorded by the US Geological Survey in the past week. All of this is scheduled to be shut down this summer unless funding is restored!