There are indeed a few practical applications. Next to Berkely lights, there is e.g. the LabChip from PerkinElmer that separates DNA and proteins. I had hoped that there would be many more examples by now. Most presentations that I see about microfluids still go in a lot of detail on how difficult it is to make. This hasn't really changed over the last decade, which signals to me we still need quite some innovation to make this mainstream.

If you want to play around with digital microfluids at home, check out the OpenDrop from gaudi.ch (http://www.gaudi.ch/OpenDrop/). I haven't played around with it yet, as I haven't found a practical use of this.