The following is more of a personal bookmark list of articles and howtos about SDR applications:

• ‘FM Radio’ (simple FM reception and transmission example in rad1o wiki)
• ‘Reversing Bus Telemetry’ (decode live information signals from bus stops in Paderborn, Germany)
• ‘Sniffing GSM traffic with HackRF’ (GSM channel detection and decoding using Wireshark/GSMTAP)
• ‘Converting Radio Signals To Data Packets’ (shows the signal isolation and decoding workflow, with further links)
• ‘SDR with HackRF, Lesson 8: On-Off Keying’ (video tutorial by Michael Ossmann about analyzing a garage door opener remote)
• ‘Receiving NOAA APT weather images with Linux’ (shows the image capturing workflow using Linux tools)

Other resources helpful when dealing with SDR:

• ‘Signal Identification Guide’ and the digital signals category
• ‘Modulationsverfahren zur Sprachübertragung’ (in german)
• ‘Practical tricks and tips’ on using GQRX (explains UI and options of GQRX)
• ‘gr-fosphor’ (improved spectrum view component, needs OpenCL)