This was a popular virtual (online) scavenger hunt we did for Sony Epic artist Cher Lloyd that is worth looking at. The ideas was to promote Cher's visit to the U.S. by having fans compete to "unlock" various East Coast cities (a West Coast edition was also created after the success of the initial scavenger hunt). Fans could compete by unlocking clues (widgets - see below - on a variety of partner sites).

Each day fans were given clues as to the location of the widgets.  Their goal was to find the widget, click and share the widget to add it to their account.  The first 10 winners in each cities got to see Cher at a special radio show performance.

The campaign also had support for physical activations using QR codes.