gStrings (cohortor.org) - Ever been caught at a rehearsal, or even worse a gig, without a tuner? Fear no more, gStrings offers a nice chromatic tuner. Included are optimization settings for a wide range of instruments (including guitar). The general feedback is that its as good as any affordable tuner in a music store. While actual accuracy hasn’t been published, in my tests I was able to tune up accurately to my ear. The interface looks nice as well but if you don’t like it 7 additional skins are included. Two thumbs up!
JamBox (intermedi8 GmbH) - JamBox is a chord computer for your Android which includes playback of selected chords when you shake your phone. It even includes a nice selection of “special” chords including popular inverted chord forms. The icing on the cake? JamBox also contains a display of scales and modes for quick reference.
Tabular (Cristian Esquivias) - I must admit that I’m not a big fan of TAB much preferring sheet music. That being said, Tabular offers a TAB search engine displaying you search results on your Android. You can even save your favorites. Be forewarned that Tabular isn’t responsible for the accuracy of the returned TAB and your subject to the same often incorrect versions available from a multitude of sites.
Gibson Learn & Master Guitar - While its true that this app is a thinly veiled advertisement for Gibson’s DVD series by the same name, its still chock full of functionality including a multifunctional tuner (modes for chromatic, standard, and various open tunings), metronome, small chord library, and several video lessons for the beginning guitarist.
Pandora (Pandora.com) - While not specifically a guitar based application, on of the first and foremost rules about becoming a better musician is to listen to a bunch of music. Pandora creates stations based on user selected artists or songs and “learns” your tastes over time as you rate music. I’ve been a long time Pandora user on my PC and love it on my Droid. Its turned me on to tons of artists I would have never found otherwise.