Just thought i would post this as I had not heard of it and thought people might be interested?
LR/Enfuse is a Lightroom plugin that allows you to blend multiple exposures together directly from within Lightroom by using the open source Enfuse application.
With LR/Enfuse you can:
Blend images of different exposures together in order to create a natural looking image with a greater dynamic range.
Blend a series of images where the focus point is difference in order to create an image with a greater depth of field – this is a common approach when creating a macro image.
Blend a series of images for night photography image stacking in order to create an image with a longer exposure than is possible with a single frame.