While desoldering useful components off of old computer hardware, I found quite a large number of 14.31818 MHz crystals.
This seemed odd to me. Why use such an irregular frequency with a very nontrivial conversion to human time units?
At first I thought that it must be a multiple of another frequency with a certain dedicated use (such as 44.1 kHz commonly used as an audio sampling frequency), but my guessing only led to two numbers pretty close to it: 1/7*10⁸ Hz and π/22*10⁸ Hz, both to about 2‰, and I can't seem to deduce what any of these would be useful for.
It is exactly 4× the NTSC color-burst frequency of 3.579545 MHz. Since it is (well, used to be) used in huge quantities in commercial color TV sets, it is both commonly available, and particularly useful when you want to generate a signal to be displayed on such a TV.