Ysearch.org is a free database of family DNA.
Excerpted from the website:
Much has happened since Y-DNA testing first became available commercially through Family Tree DNA in February of 2000. Many thousands of people have tested to find family connections as well as family origins. Since then, other labs have entered this market, and the number of tested individuals is growing as the use of DNA is becoming more and more accepted as an important tool for family research, enhancing traditional genealogy research methods. In order to allow people that have tested with the different companies to make their results available for comparison, Family Tree DNA is offering Ysearch as a free public service. read more