Ultimate-Guitar.com is more than a website, it is a full-featured online community that includes lessons, articles, forums, tabs, interviews, news and reviews. You will have a difficult time if you are looking for a mentor, though.
GuitarPrinciples.com includes popular songs in lessons from beginner to advanced. GuitarPrinciples.com has lessons for every type of guitarist and also a newsletter.
GuitarNoise.com's easy navigation makes it simple to find chords for popular songs no matter your level of play. GuitarNoise.com also has forums, a blog and a podcast to provide you with firsthand information about learning and playing guitar.
GuitarMasterClass.net has style. Learn country or the tapping techniques that are growing in popularity. Select your playing level and guitar type to get lessons suggested to you.
FreeLicks.net is the site of Kristopher Dahl, a relatively new guitarist from Sweden who will astound you with his playing ability. Learn his techniques and join in forum discussions.