"In his introduction to “Merge to HDR in Photoshop CS2” Michael Reichmann does a great job of explaining dynamic range limitations in photography and the ways to overcome them. Photomatix provides a nice little FAQ about HDR imaging as well as a few dynamic range increase examples.
"For Linux users, PFScalibration provides an implementation of a method for the recovery of high dynamic range images from a set of low dynamic range exposures such as the JPEG files produced by the generally available digital cameras..."