This years first Website of the Day is Familysearch.org.
Familysearch.org is a genealogy website run by the LDS. They are free, and have an amazing number of records indexed and record images available. According to the latest email they sent out (Dec 2011), they have apparently indexed 692,038,100 records. 153,013,100 of those records were completed in 2011.
There are records from pretty much every location and time period.
Some records are available as images only, which you navigate rather like the microfilms. In time these records will be indexed, but the website makes them available to those of us who just can't wait for that and are willing to take the time to browse the images.
I am both an indexer and arbitrator there.
Please consider volunteering to index and/or arbitrate there to keep this great site growing.