How do I implement a digital FM receiver using an RTL-SDR dongle?

Implementing a digital FM receiver using an RTL-SDR dongle involves capturing the FM broadcast signal at its RF frequency (88-108 MHz), digitally downconverting it to baseband, applying FM demodulation, filtering and decimating to audio sample rate, and outputting the demodulated audio. The complete signal processing chain is: (1) Configure the RTL-SDR for a sample rate of 2 MSa/s (providing 2 MHz of instantaneous bandwidth around the tuned center frequency) and tune to the desired FM station's frequency. (2) Apply a lowpass filter with approximately 200 kHz bandwidth to isolate the single FM station from adjacent channels (FM stations are spaced 200 kHz apart in the US). (3) Decimate by 10 to reduce the sample rate from 2 MSa/s to 200 kSa/s. (4) Apply FM demodulation by computing the instantaneous frequency of the complex signal, which is the derivative of the phase: demod = d(angle(signal))/dt = (I x dQ/dt - Q x dI/dt) / (I^2 + Q^2). In practice, this is implemented by multiplying each sample by the complex conjugate of the previous sample and taking the argument (angle). (5) Apply a de-emphasis filter (75 microseconds time constant in the US, 50 microseconds in Europe) to restore flat audio frequency response. (6) Decimate to 48 kSa/s audio sample rate with an appropriate lowpass filter at 15 kHz audio bandwidth. (7) Output to the sound card. This entire chain can be built in GNU Radio Companion using approximately 6-8 blocks in under 5 minutes.