I used to like GrowlTunes, but these days Growl has lost its shine - and frankly, you don't really need it on Mountain Lion anyway.
But I still like to see the current playing track flash up in the top right corner, for just a moment. It irks me that Spotify doesn't do this by default, and after looking around a bit I couldn't find a solution that I particularly liked.
So I wrote this very [very!] simple one - an Apple Script. Run it up when you run Spotify, and the current playing track will always be displayed in Notification Center.
It isn't particularly sophisticated, and works out when to check what track is playing by calculating the time remaining to play on the current track. Pause the track, and it'll display the same track name again when it thinks it has finished. I wrote this back in September last year, and I can't remember why I had to resort to doing that - and right now I can't be bothered to work it out again. It works, for me, for now :-)
Maybe it'll work for you. Maybe you can improve it!