Add a feature that allows bands, or venues to upload where or what they are playing soon.
This will allow users to find and listen to music that they can go and see live.
It can be monetised by either selling tickets directly or by linking to the vendor websites. IMHO free venues and gigs should also be listed though, this will help to increase exposure for local artists and help keep the gig scene alive and kicking.
Users could use geolocating or even just select what cities or locations and range the user is interested in.
This could be a killer feature that will once again separate Spotify from the crowd.