You spoke about GarageBand the music website in your post. The whole - to upload music, you had to listen to 5 random bands with no cover images or band names - just music.
I always thought that was such an interesting concept. After you did that, it would show you the names of the bands and the album covers, and you could follow and download them. It was amazing the difference in stuff I liked musically with this audio-only showcase.
Sometimes I would see the name and artwork afterwards and realize I never would have chose to even click on the track otherwise. So I ended up finding some cool music that way.
I always thought that was kind of fun. I don’t know if it’s still a great idea, but it does drum up interaction and discovery.
Also, I have a weird connection with Garageband. My bass player, Cliff, was in the band Monovox that won the record deal contest they had back then.
Although it went south. 
Let’s just say they got to go to record the album in LA with Jerry Harrison (Talking Heads) producing it. Then GarageBand went bankrupt, and the album was never released. They actually just got the rights back to the album a few years ago.
So Garageband didn’t know how to be a label, but I still think that was an interesting concept for joining the website.