While Apple clearly has a big thing going for its iPhone and photographers tend to love the phone, plenty of photographers have Android-based phones as well. Clay Cuckoo Software just launched an Aperture Clock Widget that Android-toting photographers are bound to love.
The Aperture Clock Widget shows aperture values (f/2.8, 4, 5.6, 8, 11) on the clock face instead of hours. Additionally, as the time changes the aperture blades on the clock face will open and close accordingly.
Looks like they saw this http://www.gizmodo.com.au/2010/10/f-stop-watch-measures-the-minutes-in-aperture-numbers/ and ripped it off to me (post was a few days ago, around about the time it would take to develop an app like this)