Agile Partners (who've come up at TUAW a few times) have released GuitarToolkit 2.0, a major upgrade to the original app which adds extensive features and an iPad version. GuitarToolkit boasts a range of tools geared at guitar and bass players, but now includes enough flexibility to work with any fretted instrument you can imagine. This is a free update for existing customers, and additional functionality is available as a one-time, US $4.99 in-app upgrade.
In addition to being redesigned to take advantage of the iPad's size,
