ER Diagram Tool
It would be really cool if RedGate would consider building an ERD Tool that would allow you to visually design your database schema using drag and drop before deploying to SQL Server (either generating the deployment script or deploying directly from the application)
@al gruver - SQL Dependency Tracker does just that. It's not an ERD tool in the sense that you can make edits to the diagram and push these changes to a live database, but you can reverse engineer from a database to create a diagram.
Al Gruver commented
I would love to also see the ability to reverse engineer an ERD from an existing database via a Redgate tool.