A few years ago, I created the website scwnyc.stuy.edu for the Stuyvesant High School History Department, and I maintain it to this day. The site primarily serves as a repository of student research into New Yorkers who fought fascism during the Spanish Civil War, complete with content tagging and advanced search capabilities. It also contains the first English-language interface for navigating the COMINTERN archives relating to the war (which had only been in Russian until then). I’m quite proud of it, as it runs on an annual budget of $0 and has a fairly complex home-brewed CMS!
A biography hosted on the site
An example of searching for veterans of the war who'd go on to fight in WWII
A view of the interactive map focused on volunteers tagged with "Author"
A view of the COMINTERN archive browsing tool