UPDATE (March 2012): The Transit of Venus phone app is now available for free download:
To appeal to a large audience and to have extended utility, the phone app would serve users before, during, and after the transit. Prior to the transit, participants could practice timing the contacts using personas and local circumstances of past explorers. Additionally, users could see predicted times of contact for their respective locations.
During the transit, the phone app would connect to a live webcast of the transit of Venus. Registered users could depress a phone button at the moment of internal contact (when Venus appears within the sun, just touching the sun's edge), and the app would record the exact time and user's location, which would be sent to the global database.
After the transit, users can access their data on a map, edit their entry, and upload descriptions, text, images, or movies. Other users can comment on entries.
Please join this effort spearheaded by the non-profit Astronomers Without Borders.
UPDATE (March, 2012): The Transit of Venus phone app is now available for free download: