Masking the mains hum to improve anonymity
I believe it's possible to get location information from 50/60 Hz hum, particularly if the recording is long-duration.  See this paper by Catalin Grigoras from 2009.

One way to defeat this would be to add enough sampling rate jitter to your recording so as to swamp the small variations in mains hum.  That paper showed information from variations of around 1 part in 1000, with sampling every 10 sec or so.  If you let the sampling rate of your signal drift around randomly on that kind of scale (which would have no perceptible effect), it would obscure the variations in the hum.  

So, for instance, if you let your sampling rate drift by +/- 0.1% (e.g., 44,050 to 44,150), with a maximum rate of change of, say, 1 Hz in 10 sec, that would impose a random component on top of the underlying power-grid-derived variations, making them hard to separate.  This modification would be completely inaudible.