Now ...I'm a bit biased. Well a lot biased, in fact. But the traditional mandolin player, tuning her or his instrument GDAE will not find a better free resource than the tablature archive in the mandolincafe. Click here
(If you're the slightest bit interested in why I stress the fact that I might be biased - and you're familiar with the 'cafe's tab archive - then type "derrymacash" into the search box and all will be revealed.)