911 Tabs has one of the largest database of tablatures on the internet. It is a meta search site that searches and sorts results from a large number of other major tablature web sites.
The site efficiently displays the search results by number of tablatures available for each song and by instrument (guitar, bass, drum, piano, […]

This is one of the better tab/chord search sites on the internet. The search results are nicely displayed and well formatted.
Chordie.com also has a useful key transposer and chord charts that comes in handy. The chords are often done in bold blue text making them easy to view.

Folk of the wood provides a good explanation of how to set up the fiddle, tune it etc. as well as providing some good beginner/intermediate lessons on specific tunes. It mostly focuses on bluegrass/traditional tunes such as red haired boy, whiskey before breakfast etc.

It has good lessons for mandolin, mandola, violin, fiddle, guitar and banjo.
Below […]

Acoustic Guitar Tablature
Actually, the term acoustic guitar tablature is a bit misleading because whether for acoustic or electric guitar playing, guitar tablature provides an easy way for guitarists to read and share music. There is some debate about whether or not guitarists should learn to read music or if tablature alone is sufficient.
Since the internet […]

Guitaretab
Guitaretab is a guitar tablature site with a limited number of tablatures but the layout of the site is pretty good and it’s easy to navigate around.

Ultimate Guitar

Ultimate Guitar contains a lot of useful resources in addition to guitar tablatures - including guitar lessons, reviews, forums and contests.  The tablatures are well formatted and it’s a pretty easy site to use.