From Primeleaf Consulting:
Krystal DMS Community Edition is a scaled down version of enterprise document management system. It is easy to use, powerful and completely free document management software that allows companies and individuals to centralize the management, storage, retrieval and distribution of documents. Helps people store and retrieve documents with ease and intuitiveness. With the latest version there are no limitations on number of users, and you can store up to 5000 documents. Some of the key features include: Document Retention & Ageing; Subscription and Notification Lists; Task Lists; Events Lists; Announcements Lists; Discussion Boards; and Detailed Audit.