Hawai'ian History by Island

O'ahu

• Honolulu Hawaii History - a collection of old images of and about the town.

• History of Oahu's Harbor - lengthy and pretty darn complete.

• Lonely Planet World Guide | Destination Oahu | History - decent general overview.

Maui

• AHEM - Alliance for the Heritage of East Maui - This group was a bit hard to shoebox - they are trying to preserve history and culture of their community.
• MAUI CULTURE, HISTORY AND HAWAIIAN HERITAGE - navigation is a bit weird, but using the left frame, you can click through to a fair chunk of information, as the title suggests.

Moloka'i

• Molokai, Hawaii - History and Culture on The Most Hawaiian Island. - more culture than history, but interesting. :)