Database documentation is one of those fun things that everyone loves to do, ok not really. It is usually difficult and hard to do and if there are changes to a table schema or stored procedure, you can't really query the database to ask it what was changed.
Along comes Red Gate with their SQL Doc utility to make our lives easier in the database world anyway. I gave this a try earlier this year and documented every database on every server. The cool part is that it'll show you all the dependencies between objects and generate scripts for all the objects to re-create them. You can output the documentation in HTML format, Word Document format, or my favorite a CHM help file. The CHM help file seemed to be the most useful to me as I could easily search on every item in the database on the server. The process doesn't take an extraordinary amount of time to compile either. So when you first design a database, you can create a documentation snapshot. Then you can snapshot the documentation again after changes or whenever you need to troubleshoot or want to see the latest info.
It would be really cool if the utility could just tell you the changes from the original configuration and who changed it, but that will require some type of auditing. However, you could use a document differencing utility and compare version of documentation to find the deltas.
Go check out the utility and see what you think. Red Gate offers a 14 day trial to test drive it.