If your ear is not as fine as you would like it to be, do not worry, because it is not necessary for you to try again and again to try to pick out the chord that you are looking for: Chord Pickout will tell you it in an instant!
Chord Pickout analyzes the melody of a song and shows you the correspondent notes of chords in your guitar. From the options menu you can even see a diagram that will tell you the position of your fingers on the guitar so you can play the notes!
The format of archives that this program supports are the following: MP3, WMA, OGG, AAC, M4A, WAV, and audio CD's.
Trial version lasts 21 days and will show you only the first 35 seconds of a song.