[ALUG] Document Management Systems

Does anyone here have any experience/recommendations for web-based document management systems? Ie: a collection of users, each with (secure) access to different sets of individual and shared documents, via a web interface. I know there are several wheels out there which I could avoid re-inventing, but I don't have any first-hand experience of any of them. -- Mark Rogers // More Solutions Ltd (Peterborough Office) // 0845 45 89 555 Registered in England (0456 0902) at 13 Clarke Rd, Milton Keynes, MK1 1LG