PopPhoto has an article about a new application called Helicon Focus that can aid photographers attempting to achieve extreme depth of field. (See the manufacturer’s site here.)
It looks like it could be a handy tool if it works as well as PopPhoto says it does. The process is one of taking multiple shots at different points of focus and then importing them into the software. It then combines the images to achieve a depth of field you would not be able to get with a single shot.
Though its uses may be somewhat limited (it wouldn’t work on a moving subject), it could be useful for macro, still life and landscape photographers who are willing to take the time required to achieve this effect.