ABRSM Exams Board - lots information about exam syllabuses etc.
http://www.abrsm.org/?page=exams/gradedMusicExams/latestSyllabuses.html         

GUITAR JUNCTION - We're lucky to have this great shop in Worthing, it's one of the best around. Go and see Mr David Crozier and his staff - don't forget your wallet!
http://www.guitarjunction.com

If you have any pain in your wrists, hands or fingers due to over practicing DO THESE EXERCISES!! I do them regularly anyway just to keep things moving. The guy in the video is a drummer - but don't let that put you off! They really work and can prevent more serious problems.
http://www.youtube.com/watch?v=hUyMNyrOHJQ

MUSIC THEORY This site run by software engineer Ricci Adams in the USA is excellent. General theory lessons and a guitar fretboard trainer. A labour of love apparently as there are no bannners or income generation on the site. Send him an email to say thanks!
http://www.musictheory.net/index.html

FREE SHEET MUSIC This great site has loads of music in PDF form, Classical, Jazz and Popular Music much of it completely free.
http://www.free-scores.com

THE MUTOPIA PROJECT - More free downloadable Classical and contempary music.
http://www.mutopiaproject.org

PETRUCCI MUSIC LIBRARY - the Wikipedia of classical music. More free music that's in the public domain. I've just linked the guitar page.
http://imslp.org/wiki/List_of_Compositions_Featuring_the_Guitar/Lute

BUSKING RESOURCES - Fancy braving it out on the street to entertain the great unwashed. This site has some useful links and tips.
http://www.vocalist.org.uk/busking_links.html

RICHARD DURRANT - the amazing talented virtuoso guitarist from Shoreham. He's in a class of his own.
http://richard-durrant.com