I've been a Napster subscriber from some time and they are actively engaged in a version of this. They have two tiers of music: "free to stream" and "purchase o

I've been a Napster subscriber from some time and they are actively engaged in a version of this. They have two tiers of music: "free to stream" and "purchase only or :30 preview": they have gotten into the habit of moving tracks from one category to the other as they get popular or in some cases pulling entire albums from their catalogue for unexplained reasons. While I'm sure what they are doing is legal it still is a shady "the first hit is free" type business model. So far the annoyance has been minimal as my tastes are not too mainstream but it still pops up far too often.