In my opinion rainymood is much better than this. After listening to raining.fm it became quite obvious that it's on a very short repetitive loop. Rainymood is a much longer loop and actual feels like you have your window open on a rainy day.
Another bonus point for RainyMood comes from the daily music suggestions. They even choose music from video games and anime. I've found out some great tunes from them. Example: http://www.youtube.com/watch?v=HMnrl0tmd3k
