Drag the .aco file into Add-O-Matic and it will appear in the color swatches palette in Elements. Photoshop users can just load either the .aco or .ase file like usual.
What can you use it for? It’s a great place to start with your scrapbooking projects, for a nice blue-based page. It’s also a good place to start creating a CSS-based webpage color scheme.