What are the principal uses of an op-amp RC active filter in amateur circuitry?

Operational amplifiers (op-amps) combined with resistors and capacitors can form highly effective active filters. In amateur radio, the frequency response and bandwidth of standard op-amps are typically limited to the audio frequency (AF) range, making them ideal for shaping the audio bandpass in receiver circuits, such as creating narrow CW filters or filtering out noise. Distractors suggesting their use for transmitter low-pass filters or blocking RFI at receiver inputs are incorrect because RF power and high radio frequencies require passive components (heavy-duty inductors and capacitors) that can handle high power and wide bandwidths. Power supply smoothing also relies on large passive components, not op-amps.