Can anyone recommend a good document management system?
It depends on your needs. If you are looking for an enterprise document management solution, then documentum would be worth looking at. I have not used it my self, but everytime I hear someone mention enterprise level document management then it is useually followed by someone recomemnding documentum. If you just need a lite document management system then Microsoft SharePoint may be able to meet your needs, but I would recommend not customizing it at all.