(Disclaimer: I work for Extensis)

Extensis Portfolio stores metadata in a database for fast searching and has an option to write metadata into files. The software supports XMP, EXIF as well as IPTC and automatically extracts GPS and the date/time taken. Photos can be organized into galleries, tagged with keywords, or you can create your own custom metadata fields and tags.

There’s also a server version available for multi-user workgroups/enterprise.

(Disclaimer: I work for Extensis)

Portfolio Server can continuously index files on SMB/CIFS (and AFP) volumes using a feature called "AutoSync". Web and Desktop (Windows/Mac) clients then search by folder name, file name, document text, or other metadata. Indexing and thumbnail creation takes place on the server, so clients are relieved of any cataloging workload and metadata is centralized.

http://www.extensis.com/en/products/portfolioserver9/overview.jsp