There's loads of different variations of this haunting guitar-played main theme. I settled for this exactly minute-long version I really liked. I couldn't instantly find it on youtube, but it plays as menu music on my Unforgiven DVD so I trust it's also found on the soundtrack. It's fairly easy to make longer versions off this bit by repetition etc. if need be. Can be played in any key, but at least in C it sounded real nice.