https://www.rtl-sdr.com/ is a great site for updates on new hardware and software.
Most commonly, I use my SDR for: - Listening to ham (amateur) bands - Receiving NOAA/Meteor satellite images - Airplane tracking
There are quite a few other use cases, which I've outlined in several talks that I've presented at conferences over the years; https://github.com/tomswartz07/CPOSC2017/blob/master/Softwar...