For someone who can not play nor sing good, like myself, Melodyne is a very useful tool. It works with audio as with MIDI, so it gives a possibility to modify any note, including pitch, amplitude and drift. Sure, it introduce sound artifacts, especially with extreme settings. But for noobs that is not important and pro do not have to deal with drastic mistakes.
In general, that program is graphic oriented. But looking precisely I have noticed it delivers sufficient information and supports several shortcuts. Still, the whole interface is one window without any accessibility in mind. Usual approach just with automated mouse clicks is no go.
Sibiac was developed just for such cases. And now you can check it in action with Melodyne. The overlay is just released, so untested. I am sure there are some bugs.
Instructions and documentation: http://www.azslow.com/index.php?topic=427.0
I have also quick recorded a presentation. From which you can easily conclude that I am not a good guitar player, my English match my guitar skills, I probably just got a cold and I am rather tired from making this release. But I hope you also can notice that the thing can work http://www.azslow.com/files/Melodyne_Intro.mp3