Offered in Beta from the Office of the Law Revision Counsel of the United States House of Representatives, this new website offers excellent access to the Code.
The US Code is an official consolidation of Federal US Laws by subject, and highly useful. Its various accessories, such as the indispensable Popular Name Tool make it a first resort of legal researchers. The online version, and various commercial print versions, are not considered official for US courts. However, this particular online version will likely be the most up to date version of the code, given its provenance.