Here is a great idea for using mobile phones to allow people to volunteer time for all sorts of tasks that it percolated to the top in an open competition for innovative “Changemaker” ideas. It has a NESP-like flavor to it, although with a focus on short-term (20 minute) tasks that people can quickly select and accomplish. This is in contrast to the NESP vision of long-term participation in medical research studies that researchers select the volunteers for.
(There is some interesting information on the project website, everything from a nice intro video of the idea to links to the use of game mechanics for social media. You can also sign up for their newsletter)