Hi Brandon,

Check out Enterprise Architect from www.sparxsystems.com 

I've been using it for years. Just a satisfied customer.

Kimbo

You might look at analytixds.com - it is a full scale data mapping suite, with the ability to maintain business rules, do impact analysis, data lineage, etc..  I disagree that it is hard to beat excel - yes it is versatile, but it is a lot of work to build things into it, and get things out of it - especially if you are trying to be consistent with multiple analysts on a single project.   The Mapping Manager software covers everything pretty much in the design phase and pushes your designs into the ETL layer directly...