Because Spotify's music browsing sucks. Also, I can listen to last.fm recommendations in Spotify that way.
What do you need?
Some way to run user scripts. Either
- Greasemonkey, if you're using Firefox
- GreaseKit, if you're on Safari (not recommended since it's very hacky to get plugins run in Safari)
- Use Fluid.app to create a site-specific browser for last.fm
What's left to do?
It only support artist links so far. Need to add that little icon to album