At the Home view, there's different ways to sort albums, one being "Most Frequent". It would be nice to offer my users another option called "Most Popular" which shows what people are playing a often but the difference between the two would be that, after an album isn't played as much as it used to be, it falls down the chart. This could easily be done by giving an album a value and each song listened to adds 1 to the album's value. The difference would come from a part of the equation that removes points from the value as time passes. For example, album X is being played 50 times a day and thus is gaining 50 points per day but is losing 5 points per day (like all albums) until it reaches zero. Once X becomes less popular, the net change will eventually take it to zero.
There's much more intelligent ways to do this like with exponential decay that will change itself according to the average number of overall song plays per day but the example above was just to give an idea of what I'm talking about.
I'm not even sure if this is possible but it would be fun to be able to see how music tastes trend.