I am actaully not too bad at composing music for the guitar. I usually stumble on something while I'm practicing or fooling around. But I have a problem; I have a terrible ear for other's music. I cannot for the life of me figure out guitar parts for already recorded songs. Some of the guitar pieces I would like to learn aren't available in the bands books in like Guitar Center or in tab format. I have a question; Is anyone aware of a site (online) where I could have someone record the guitar part of a song so I could see it played? I know it sounds odd but it is something I would be willing to pay for. In fact if I was able to figure out popular pieces I would prepare the videos myself for others (for a fee, of course). I have found out when I have a question someone else has already asked it so maybe there's a simple answer.
Depends on how you filter your searches.
I know of no one site that has it all.

You must have an ear if you can compose. Your issue may be as simple as practice.
Start looking for ear training sites or programs.