Two of my favorite Photoshop experts, Ben Willmore (Digital Mastery, The Best of Ben and Where is Ben?) and Bert Monroy (PixelPerfect) get together. They meet to explain HDR (High Dynamic Range) in a two part series. A great explanation of HDR, with a walk through of the creation of an HDR image. Simple enough explanations that anyone who uses Photoshop can follow along, and with enough detail that even someone who's used Photoshop as long as I have can learn something new.