Phoneum is a new mobile phone only Crypto Currency that is currently running a free air drop, if you register here you can claim some free coins and get an account on the service.
Phoneum is offering mobile mining and a mobile wallet, and has done a good job marketing the service with it's free air drop, registering more than 10,000 users easily.
Mobile phone coin mining should be very popular, with so many mobile phone devices available it's a huge pool of CPU power going unused.