I learnt about GroupShot

Microsoft have a research department which sometimes produces some nice software that you can try. Probably the best I have found so far is GroupShot. This is a small utility that allows you to take a number of photos taken from roughly the same place and to pick the best parts of each image to make up a single composite image.

This sounds like a complicated task but they have made it really easy to use. You load in your images and then highlight the area you want to change. You then select the area from which image you want to use for that area.

On holiday I found myself taking multiple shots of the same thing just so that I have the opportunity if needed to remove unwanted parts of the images such as the kid pulling faces in the background or the tour group walking through the shot. It has already changed the way I take photographs.

http://research.microsoft.com/projects/GroupShot/