Spotify is a online on-demand radio service (atleast thats how I perceive it) that allows you to listen pretty much whatever music you want whenever you want, where ever you want to listen.
A cool new service (web app if you like) has started up to provide everybody an email alert service everytime Spotify adds new music to their library that you are interested in. Your interest can be registered by either adding artists manually or importing all your top scrobelled artists on last.fm
Oh right, what’s this app you ask and how can I access it?
In their own words
I gather it is built on top of Google app engine as it is using your Google Account to store your alert preferences. Levraging an existing authentication system, especially one so widely used, is a very smart idea for such a simple (yet useful) service. Kudos to its creator.