Banshee should calculate the Play Rate (or “Play %”) for each song, defined as:

100% × (play count) ÷ (play count + skip count)

…except when (play count + skip count) = 0, in which case Play Rate is defined as 0. (The mathematician in me wants a number from 0 to 1, but 0 to 100 would be better for normal people, hence the “100% ×”.)

It should be possible to restrict smart playlists to a specific range of play rates, and sort by highest or lowest play rate.

This would be a useful surrogate for Amarok's “score” statistic – similar to an automatically-calculated rating.

There would be no need for Banshee to collect any extra data, just to do one more simple calculation after each play or skip.

For bonus points, if I play 40% of a song and then skip it, the play count should increase by 0.4 and the skip count by 0.6.