I love advertising as much as the next content creator, but using sponsored iPhone apps always makes me feel a little bit like the Zune tattoo guy. That's true even when they're from a company whose products I admire, like Gibson guitars. (I'm the longtime and very satisfied owner of a Gibson L-4A.)
Nonetheless, the Gibson Learn and Master Guitar app, released today, offers considerable value for a free app. It's got a chromatic tuner for getting in tune, a metronome to help you stay on tempo, and chord charts for some basic open and barre chords--perfect for beginners. There are also a couple of full lessons and some video previews from the Legacy Learn and Master Guitar video series--apparently they're hoping you're impressed enough to purchase the full lessons on DVD. I'd still be willing to plunk down $9.99 for the far more complete and ad-free Guitar Toolkit app, but if you're strapped for cash and just learning how to play the guitar, the Gibson app will get you started.