Usually I add songs to my winamp playlist in a seemingly random order, choosing what I just feel like listening to from my huge collection of various mp3s. In most cases I come up with a perfect medley of neo-classics, hard, celtic, punk and art-rock, classics, heavy, progressive and symphonic doom metal, ethnic music, and other meditative, instrumental and romantic music.
Obviously, I tend to listen to more of the fresh things I have recently downloaded, yet I can listen to some special hits for months never getting tired of their sophisticated tunes and heartfelt lyrics.
My idea is developing a winamp plug-in that would count the frequencies how often I listen to some certain song, performer or genre, this way determining my musical preferences for a certain period of time and the dynamics of my preferance change. By the way, hypothetically the music preferances over a certain period of time reflect our actual emotional state, so when we're depressed or tired or in love we tend