From tornado warnings, to railroad crossing locations, to IRS tax info, to whale and dolphin identification, to keeping up with Congress...there's a government app for that!
USA.gov lists all available apps by category and/or device type. You can also search by keyword.
Congress.gov is out of beta testing and fully operational. With the exception of some historical content that has not yet migrated from Thomas, Congress.gov is the go-to site for Congressional information past and present. The old Thomas links will automatically redirect to Congress.gov, but if you need to access Thomas for the un-migrated material, you still can; just use the link below.
The new site has great new features and more content. Generally speaking, Congress.gov is set up for efficient browsing if you don't have the exact information (a bill number, for example) that you need. Just limit using their wide variety of facets to whittle your search results down.