The NSSAR is the The National Society of the Sons of the American Revolution. It is a fraternity organized in 1889 for the male descendants of patriots that fought in the Revolutionary War. During my research I've come across many of the archived forms that people have filled out over the years tracing themselves back to men who served in the Revolutionary War.
The DAR is a women's organization for the descendants of individuals who aided in achieving American independence, very similar to the NSSAR. However, I have never seen a "public" record of a DAR's membership application. Ordering them is easy and will cost about $10 on their website.
If either of these organizations interest you, you should visit our Military Page, to see if you are connected to one of the men listed as fighting in the Revolutionary War. I should also mention that these organizations are not "free" to join and do require a degree of "proof" to show that you are in fact a descendant of a patriot. Information from this site might help "jump start" your research. If you get stuck you may want to reach out to the organizations, who may already have your ancestor's information on file.