I've messed with CubicSDR briefly. There are others, depending on the SDR hardware you wish to use. One that looks impressive is SdrDx.
http://fyngyrz.com/?p=915Others include GqRx
https://sourceforge.net/projects/gqrx/and SDR# (but I think it might only be tied to Airspy hardware now. It wasn't in the past).
http://airspy.comThat said, there are far more options in the PC realm. As Mac user, I bought a PC to play with the SDR stuff. I hate to say it, but I think you miss out otherwise.