Navicat Data Modeler - Navicat Data Modeler allows users to create a conceptual model from an existing database and edit the structure of the database easily.
ApexSQL Doc - ApexSQL Doc creates database documentation in a variety of formats.
MySQL Workbench - MySQL Workbench is a unified visual tool for database architects, developers, and DBAs.
Dataedo - Database documentation tool
DbDesigner.net - DbDesigner is a web application which allows you to design your database schema without writing SQL.
dbForge SQL Complete - Try Intellisense functionality and Improved SQL Formatter in SQL Server Management Studio and Visual Studio using SQL Complete!