The Indiana University Digital Library Program has released the IN Harmony Sheet Music Cataloging Tool.
Here's an excerpt from the tool's page:
The IN Harmony Sheet Music Cataloging Tool is an open source tool developed by the Indiana University Digital Library Program with funding from the Institute of Museum and Library Services as part of the IN Harmony: Sheet Music From Indiana project. This tool has been designed to assist libraries, archives, museums, and individual collectors describe their sheet music collections in a robust and standards-based way. This is a production system of the Indiana University Digital Library Program and was used to catalog more than 10,000 pieces of sheet music for the IN Harmony project.
The tool collects descriptive metadata about sheet music and exports it in the MODS, simple Dublin Core, and OAI-PMH Static Repository formats.