Use Zero Padding to find hidden peaks
Zero-padding can be used to more accurately estimate the frequency of a single sinusoid in zero noise.  Since a zero-padded FFT produces a smoother looking plot, and thus shallower peaks, if there are any subtle changes in the inflections and thus peak location caused by noise, those shifts will be magnified by the zero-padded FFT, perhaps from a fraction of a FFT result bin to several bins of random shift.

So, one needs to have a good estimate of the S/N ratio to know whether and how much zero-padded will produce a usefully more accurate frequency peak estimate of a sinusoidal (or narrow band) signal.