AudioTag.info — is a free music-recognition service. It allows you to identify almost any unknown piece of music quickly and easily. Its use is very simple: you upload a short audio fragment (even 15 seconds are enough) or an entire song, the robot analyzes it and provides you with the information about the track title, artist name, album title, etc. Your audio fragment can be in almost any file format and of almost any quality (aurally recognizable, of course) — it can be an MP3 file downloaded from the Internet or a short recording made with your old tape recorder and stored as a low-quality .WAV-file.
Read more at the FAQ page.