Capo 3
http://supermegaultragroovy.com/products/Capo Highly recommended for anyone with a mac if you want some help figuring solos out. Guitar pro 6 http://www.guitar-pro.com/en/index.php Just massively useful with its Realistic Sound Engine that does a great job of synthesizing guitar sounds. Was that note/chord hammered on, pulled off, palm muted, an up or down stroke, a bend or a slide? What exactly is the strumming pattern? After some trial and error in GP6 I'll have it figured out in detail by comparing the original tune with what GP 6 is playing back to me. Obviously you can do the same with your own guitar instead, but I like to create customs too. Amplitube http://www.ikmultimedia.com/products/cat-view.php?C=family-amplitube Lets you set up amps and pedals and play guitar via a usb cable long before rocksmith came out. Though haven't used it in a long time now as Rocksmith contains pretty much the same functionality. SpectralLayers Pro 2 http://www.sonycreativesoftware.com/spectralayerspro Not a guitar specific product but an advanced audio editor. Not only does it render a spectrogram of the audio like Capo3, but it lets you edit the audio visually like this too, splitting it into layers etc. Don't own a copy of this, but used the trial to remove noise to try and isolate a tricky solo. If it was cheaper it definitely would like to play around with it some more in the future.