Contrast Blending Actions
The Contrast Blending Actions stack and mask differently exposed images in order to combine the correctly exposed parts of all images in the result. The result can be visually controlled by adjusting layer opacity as well as by editing the masks.
The action set is available from Erik Krause
An approach that I use can be found on Michael Reichmann's site - http://www.luminous-landscape.com/tutorials/digital-blending.shtml. I use the second technique, the Layer Mask approach, and have found that it works quickly and easily, while still leaving much room for tweaking as necessary. The only change I've made in my approach is at the end where I work in Levels instead of curves. I find that sliding the mid-tones to the right helps make the resulting image look more realistic. In some cases, you just have to play around with all three sliders until you get a good blend. I also will reduce the opacity of the top layer down to about 85% as well.
Mark Fink www.northernlight.net