[Andy A.]

Design tables! Not only can you quickly toggle between various configurations of the same part but you have access to all the math tools of a spreadsheet and your critical dimensions in an easy to view area. You can really quickly and easily view and set relationships between dimensions across multiple sketches and features, and even drive a design with a quick and dirty GUI made in the spreadsheet.

It's particularly a useful technique for stuff like gussets and brackets that you may need to frequently adapt and/or have a lot of common configurations of. Instead of a starting a whole new part file you just create a configuration with a row of dimensions inside a excel file.