How do you document your databases? I find that most of my clients are not documenting their databases at all and I find that pretty scary. To introduce some better practice, I would like to know what tools/process people are using.


How do you document your database? (SQL-Server) 
What tool do you use? 
Documentation Storage Format for database schema/meta-data?


Word documents
Excel spreadsheet
Plain Text

Documentation process or policies?


I am not talking about reverse engineering / document a existing database, but mainly on the documentation best practices while you develop your system/database.
I have been using extended properties since they are very flexible.  Most standard documentation tools can be driven off MS_Description, and then you can use your own with custom-built tools.

See this presentation: #41-Get a Lever and Pick Any Turtle: Lifting with Metadata

And this code: http://code.google.com/p/caderoux/wiki/LeversAndTurtles