Here are a few tools I found:
Dataedo http://dataedo.com (nice export - PDF and HTML, nice features)
SQL Doc http://www.red-gate.com/products/sql-development/sql-doc/[/url] (nice HTML)
DBDesc http://dbdesc.com/[/url] (relationship diagram)
ApexSQL Doc http://www.apexsql.com/sql_tools_doc.aspx
Documenter https://www.spectralcore.com/documenter
SchemaSpy http://schemaspy.sourceforge.net/[/url]