Collections are one of my favorite new features in Adobe Bridge CS4, which comes bundled with Photoshop. In this screencast, based on Chapter 3 of The Photoshop CS4 Companion for Photographers, Derrick shows you how Collections add the flexibility to Bridge that we've been waiting for. Plus you'll learn how to build Smart Collections based on a variety of search criteria.
If you haven't heard of Collections before, they are virtual folders that you can use to view your pictures in various groupings without compromising the integrity of your organizational structure. So you can pull a picture from here and from there, put it in a Collection, and use that for display or publishing. When you're done, you can discard the Collection, and there's no impact on your organizational folders. This is good stuff!