The T-10 award-winning app has potential for communication between people on the International Space Station (ISS) and Earth (see http://spaceappschallenge.org/project/t-10/). Through this app, astronauts on ISS can be alerted through smart devices, when the ISS passes over particular localities on Earth and when photographic conditions are just right. This allows people on Earth to be alerted to the precise time when ISS passes over and this allows them to wave at astronauts on ISS at just the right time. This is a great advancement in synchronised communication -- the result of the 2013 Space Apps Challenge.
If we can wave at ISS, then perhaps we can dance, or even sing. If this app allows capture of a visual image through photography, then what would be the sonic equivalent? Perhaps a recording device and communication through Tweets at the exact time ISS takes the photograph? A great musical challenge.