SoundCloud is an application that allows you to record any sound with your Android device, in order to share it within seconds through any social network such as Facebook, Twitter, Tumblr or Foursquare.
The best part about the application, however, are the possibilities SoundCloud itself has as a social network, being that it allows you to access and listen to the recordings of the rest of the users, and score them giving them point values and comments.
All of this music can be heard by streaming directly, for which you'll need a good internet connection over 3G or WiFi in order to access. As you cannot always have internet access, the application allows you to record a sound at any moment and upload it to your account later.
SoundCloud is a very interesting application that not only allows you to record a fragment of a song at a crucial moment to remind you later, but it also serves as a recording device for reminders and hundreds of other things.