Hi Nicolas,
Yes, there a couple of websites specializing in Philippine tribal stuff. For example:
http://home.chello.no/~andy.anderson/Page2.html
IMHO, it would be a challenge for anybody to come up with a good representative collection that would cover the entire peoples of the Philippines, as we have around 120+ cultural groups. A lifetime might not be enough to adequately study all these groups

Thus, scholars tend to specialize, which I think is a wise route.
Anyway, your site is cool indeed!