The National Archives is going all tag-arrific on us:
The Online Public Access prototype (OPA) just got an exciting new feature — tagging! As you search the catalog, we now invite you to tag any archival description, as well as person and organization name records, with the keywords or labels that are meaningful to you. Our hope is that crowdsourcing tags will enhance the content of our online catalog and help you find the information you seek more quickly.
Nice! (Hat tip to Infodocket for the tip)