“The Federal Register is the official journal of the federal government of the United States. In it, you’ll find any kind of proposal, notification, or solicitation for data that a federal agency puts out.” It includes Presidential documents – including Executive Orders; current and proposed Rules & Regulations; and Notices.
The Register is currently available online, through GPO Access, but that site does not allow you to search all available content at the same time – the current year is available in a separate database. A group of software developers has put up an alternate website that allows you to search or browse the Register from 1994 onwards in a single (much more attractive) interface. You can browse by date, topic, agency or location.