I think that maybe you should explore the thought of why this is a 'lost' continent. Implying that it was at one time, 'found' or central in focus. Perhaps something happened to the land itself making it deadly to its native inhabitants. Most of them perhaps fled, though a few (one particular culture left behind adapted?) were able to eke out life, remaining involuntarily behind. This gives you great options; language being the first and formeost. civilization another.
Perhaps only 'little people' were left behind. The land became toxic (swamps, sinkholes, noxious low-lying gas clouds, ground-burrowing bulettes?) and those who were not killed learned quickly to take to the trees. A whole civilization was left behind to live above ground, in the canopies of native foliage. This alone lends the possibility of whole new prestige-classes, skills, and feats (think about it). The 'Gulliver's' could be oddities among the shorter 'tallfellow' derivative race of halflings that they so closely reflect in larger-than-life view. Does this make them Gods? Or perhaps a prophecy of false gods?
And what if the PC's get deep enough into the exploration of this lost continent and discover the indigenous life, how do you communicate. Perhaps some words are similar or in common while others are not, mean something else, or are totally foreign. Generations of separate evolution will be hard to bridge. Challenges that can't be met head on with strength and steel always appeal to me. And do the altruistic PC's hope to help rid the land of whatever drove these peoples to the trees? Will this hinder those peoples by destroying some unkown symbiotic relationship, thus causing the PC's to have suddenly acquired some unanticipated enemies?
I think that you are in store for a wealth of great potential and fun...
