Here you'll find the links mentioned in What's Clickin'
If you love researching your family history, the 1940 US census is a must-see, and it's now available online for free. At this point you can't search by name, but using an address or general location can narrow down results.
The records just went live April 2nd and already the site has tens of millions of hits. The 1940 census is the single largest collection of digital information ever made available online by the National Archives. New census records are made available every ten years as confidentiality restrictions expire.