PBCore is a metadata standard for use with audio visual materials brought to us by the Corporation for Public Broadcasting. Based on Dublin Core with element sets expanded for improved description of broadcast specific fields, PBCore can be empoyed for digital asset management for any media collection large or small.
What I like most about this standard and the website overal is that it clearly explains how to adapt existing systems to incorporate PBCore to promote greater consistency and allow interoperability and sharing as well as how to go whole hog in creating a system entirely based on PBCore. It all depends on how much metadata is appropriate for your particular application.
PBCore is free for use (Creative Commons license model) and the primary focus is on helping media managers create metadata to improve findability, encourage ease of reuse, and sharing. This standard is simple to use even with a basic Excel spreadsheet and can be used with databases like Filemaker. Many DAM systems can be mapped to the PBCore elements too.