I work with many clients who have layers of business contacts. A common requirement is to link contact to contact records from different sites via some type of relationship. These could be work related for employment details for people such as managers, etc. Or they could be company related as in HQ, Region HQ, Storefront, etc. I can do this by creating an extension to add fields, however with a few additions to the Business Relations feature, it could handle the complicated business relations all companies have.