As you may have heard, Rdio is shutting down imminently. As a long time Rdio subscriber, this was pretty sad news to me. It seems the obvious replacement is Spotify, but there didn't seem to be any good way to migrate an Rdio collection to Spotify.
Enter RIP Rdio, a little web app I cooked up to help you transfer your Rdio collection. It uses an export CSV file that can be produced by this Chrome Extension. Once you have that RIP Rdio will lookup and add all the albums or tracks from your Rdio collection to Spotify's "Your Music" collection.
If this sounds helpful, please give it a try and let me know if it works for you or not. If you are interested, the code is on Github. It's written in Go with the frontend largely ripped off from the Spotify web api example project.