Free Guitar Music

The Classical Guitar School, Iceland
Classic Guitar Pedagogy - a website for lovers of classical guitar in general and particulary suitable for teachers of this instrument.
Petrucci Music Library - a huge resource for out-of-copyright music generally - look for a guitar composer and see what's there. - Some free sheet music, music lessons and resources for piano, guitar, flute, violin and other instruments. Free public domain sheet music of all categories, easy to find by composer, style or instrument.

Guitar Home Pages

York Guitar Quartet - my favourite quartet - well it would be, wouldn't it?!
York Classical Guitar Society - for all York (and other) lovers of the classical guitar of any standard.
Andrés Villamil - composer and arranger with a Columbian accent.
Classical Guitar Forum
The Classical Guitar Home Page
Classical Guitar News - All the latest from the Classical Guitar World
Cambridge Guitar Orchestra
Derek Hasted Guitar Ensemble & Guitar Orchestra
Early Music - Classical Guitar Ensemble Jon Sales' page of a vast collection of free mp3 recordings of early music ensemble arrangements. An excellent resource.
GuitarBurst - a site with a large searchable database of guitar music, with grading, composers, publishers and more information.
The Guitar School - a lot of music by Eythor Thorlaksson for the classical guitar.
Jacaranda Classical Guitar
The Classical Guitar Home Page in Japan
Pasquale Mamone's L'Altra Chitarra - in Italian but English coming soon.
Midland Fretted Orchestra
Modern Guitar Ensemble - an excellent blog resource for guitar ensemble information and interviews.
Niibori Guitar Music Group
John Pickard - live solo Spanish / Classical / Flamenco / South American guitar music.
Ralf Bauer-Mörkens - composer - have a listen to some fine sounds here.

Other Guitar Publishers

Araniti Foundation - The Araniti Foundation is the first e-book publisher of guitar music in the world.
Les Éditions Doberman-Yppan (Guitar solos, duets, trios, quartets, guitar ensembles, chamber music)
Editions Orphée Home Page
Guitar in Un nuevo concepto de música para la guitarra en conjunto.
Les Productions d'OZ
Trove Music - Original works and transcriptions of composers ranging from Bach to Debussy.

Other Music Home Pages 

Cours de guitare électrique, folk, classique et formation musicale en Vendée.
Forte music notation - including Forte 6 free.
Guitar Academy - a good online resource for the pupil guitarist, well presented with clear technical advice.
GuitarPlayerWorld - Learn & Play Guitar | Free Guitar Lessons Online
iMusicDictionary - is the most comprehensive online music dictionary. Here you can quickly find accurate definitions for musical terms.
I Trovieri - An Italian school and ensemble with a good sound.

Guitar shops

London Guitar Studio - where I bought my Yulong Guo!
Gifted Musician - Music gifts for musicians and for people who are passionate about music
Yorkshire Classical Guitar - is based in Castleford near Leeds for Alhambra, Altamira, Bautista Iranzo, Jose Antonio, Juan Hernández, Paco Castillo
Stafford Classical Guitar Centre - guitars by many of the world's most talented luthiers