I think that slack key tunes in the Hawaiian style are somewhere that I really want to explore next on guitar.

Does anybody know any good websites or resources (preferably free) with tablature or sheet music or what have you? I have experience with open tunings and fingerstyle paying, but not with slack key particularly.
My God, it's full of stars!
I lived in Hawai'i for 16 years, and played guitar for the last 10 years there, in the 1970s-80s, and think it is the most beautiful, melodic guitar music in the world! I have several "ki ho'alu" slack key artist favorites that you may want to Google, like: Gabby Pahinui and his sons Cyril and 'Bla', Keola and Kapono Beamer, Peter Moon, Robert and Roland Cazimero, Sonny Chillingsworth, Ozzie Kotani, Jerry Santos, Kimo West, Israel 'Iz' Kamakawiwo'ole and the Makaha Sons of Hawai'i to name but a few.

Google Keola Beamer and you will see his "Brief History of Slack Key Guitar" with tunings and songs, and google Kimo West, and you will get a plethora of videos, including lessons. Google Hawai'ian Slack Key Tuning for pages and pages of links. You just hit the jackpot, my friend. Enjoy!

I won't steal Keola's thunder, but the Portuguese sailors brought the 'kikas' (guitar) and 'ukuleles' (Hawai'ian for 'flying flea') to Hawai'i in the 19th century, and eventually the Hawai'ians got their hands on them, and, having no tuning instruments or pianos, they tuned them to sound good to their ear, and used them to accompany their lyrics. There were almost as many tunings as songs, so be prepared to do some studying, to pick out some good ones. A lot of the slack key songs are in the key of D, like a 12-string often is, so you probably already know one tuning well enough to learn a myriad of Hawai'ian slack key favorites that will always please your audience. Hawai'ians cultivated long fingernails, because flat picks were in short supply, so most ki ho'alu is done in an elaborate fingerpicking style, which is stunning to hear and even more stunning to watch in a performance. Hawai'ians have taken finger picking to a whole new level . . .
Happy Holidays,