I know the artist and trackname for a song, but I am unsure of what service or how to download album art for the track.
I believe iTunes and Amazon both offer services but I am unsure of how to integrate these services, any links or suggestions are appreciated.
To use Amazon you'll need to sign up as a developer for their public web services.
This is mainly just to get the access key that you'll need for making your calls to their web service API.
You'll need to do a product search using the artist and album name, this will return an ASIN number. Once you have that number you can build the URL to the actual album art, ie:
http://images.amazon.com/images/P/*ASIN goes here*.01._SCLZZZZZZZ_.jpg