I often come across projects that take the following line of thought…
-> Great idea for youth market
-> Relies on having Internet access
-> Youth market is mainly pay as you go
-> No point doing as pay as you go users don’t use Internet due to high cost (usually costed per Mb)
I think things are changing. Take a look at UK 3’s pay as you go tariff. For just £5 a month you get up to 2Gb access. That’s less expensive than most on-contract tariffs.
Alternatively, look at it from another angle. At that price it’s also cheap enough to use as a second SIM just for data access. For example, one of my laptops (a Dell D420) has an integrated HSDPA 3G module. As prices drop I can also see more opportunities for using secondary SIMs in, for example, automotive and telemetry applications.