The Thesaurus Musicarum Latinarum is a database of digitized medieval Latin texts on the topic of music, broadly imagined. Housed at the University of Indiana, the project transcribes and digitizes texts on all topics related to medieval music from the 5th to 17th centuries and provides a database to house them. A user may search by title, author, topic, century, and numerous other qualities. Each text entry offers a brief synopsis and bibliography, including manuscripts in which the text appears.
The TML clearly outlines their transcription policies and provides all their material for free via a Creative Commons license.