Soundwave is described as 'With Soundwave, you can instantly and easily share what you are listening to on your phone and see what your friends, family and favorites (musicians, athletes, celebs) are listening to on theirs. Inspire yourself by plugging into your music world to see what’s playing' and is an app in the Social & Communications category. There are three alternatives to Soundwave for a variety of platforms, including iPhone, Online / Web-based, Windows, Mac and Android. The best alternative is Last.fm, which is free. Other great apps like Soundwave are streamsquid (Free) and SoundShare (Free).
Last.fm is a music community website that offers personalized internet radio, using a recommendation system called "Audioscrobbler" to build a detailed profile of users based on their music tastes and interests.