Already got that in, sorta. User ranks 1-10 and the system adjusts the weights. Having the user set their own weights on each factor wouldn't be very useful to all but the geekiest of us who would know how to use it. Right now we've just got a simple 1-10 rating scheme, tied in with the conditions under which the rating as added (time of day, calendar time, etc) and taking into account historical ratings of a song (i.e. you gave it a 7 last month, now it's a 5.) The system tries to tie in not only how often that song should be played, but what other new releases you might want to hear, etc. It's not very sophisticated yet but we're only about 1/3 the way through the development cycle, and we've only got a 15 week class to do it in. But based on the skeleton we have now, I think after two or three Creed songs, it would notice a correlation between low ratings and the Artist attribute, and adjust accordingly.