You can do amazing things with a guitar and a smartphone these days. Joe Satriani mentioned in a recent interview in Guitar World that he demoed all the tracks for his latest album on his iPhone in his hotel rooms on tour.
Ultimate Guitar Tools – Ultimate-Guitar.com brings us this guitar tool kit app that includes a chromatic tuner that supports standard and alternate tunings, a metronome with custom presets, and an expansive chord dictionary to help you find any chord you need. $3.99 and available for iPhone and Android
Gibson Learn and Master Guitar – This one, from the fantastic Learn and Master Guitar guys, is similar to UGT above. The metronome includes a tap tempo, but the chord library is a little smaller. It’s also comes with video lessons from the Learn and Master Guitar series, which are very good. Best of all… It’s free. Available for iPhone and Android
Guitar Web App – This guitar app has a terribly bland name, but it’s actually very useful. Not only is it a chord dictionary, but it also explains the relationships between the chords, chord substitutions, and good chord choices for particular melody notes. Useful when you’re trying to harmonize a melody or work with a fake book. $0.99 and available for iPhone
Guitar Fretboard Addict – Through the use of fun games and exercises you’ll learn the fretboard inside and out, plus it helps you learn ear training, sight reading, and theory. Ask me how much I paid to learn all that stuff in college. A bunch more than $4.99, I’ll tell you that much. Available for iPhone.