The US National Archives is a great treasure including a well-maintained and ease-to-use website. Sometimes I will roam around on the site to find interesting historical data, even if it is not specific to my genealogical research. However, with such an expansive resource sometimes it can be difficult to find the specific data you seek. One of the ways I try to deal with this issue is to bookmark a great find, although sometimes the link becomes inactive over time.
Thus, I follow my favorite resources by signing up for their newsletters or following them on Facebook. This allows me to keep up to date when Archives or other large databases update their materials. Yesterday, the Archives "Today's Document" posted on Facebook was a link to the Harry S. Truman Library and Museum in Independence, MO as well as a link to Truman's presidential photo archive. The National Archives digital catalog is a great resource. Bookmark it today.