At last years F-Con Jim Gatwood presented a talk titled "SDR Radio for Hackers and Nosy Nellies". The two hour talk has recently been uploaded to YouTube and covers the basics of software defined radio theory, RTL-SDRs and their installation, use of common software, GNU Radio basics, and a broad overview of various other applications including rtl_433, ADS-B and more.

If you're looking for a broad overview of the software defined radio field, and what you can do with SDRs then this may be an interesting talk for you.