This is a useful forum that I visit.  The teacher provides here a nice introduction to bossa nova on the guitar.

Frank Gambale is considered one of the greatest sweep pickers alive.

This website is a wonderful resource.  The lessons offered here are practical, simple to follow and profoundly useful.

at JazzGuitar.be

This man has taken on an inspiring goal.  He hits on some nice voicings.

at A Chord a Day

A comprehensive list of chord scales.  Major, melodic minor, harmonic minor, natural minor:

At Musilosophy.com