Hear.me would have been great for an online playlist/radio development, but I'm not sure about "Heard". From my experience/research, .ME's are best with present-tense verbs; past-tense sound awkward and diminish a lot of the potential uses for the name. You can try developing some kind of song finding service where users input lyrics they heard from a song and want to find which song it was from.
xx at best IMO