Not exactly an idea for invitation themselves, but DD's 2nd birthday was a luau and I looked everyone's name up on the site I listed below to get the Hawaiian translation. I addressed invitations using the Hawaiian names and made up nametags (attached to leis) with everyone's Hawaiian (and American) names.
Everyone really seemed to enjoy this. The people who run this site are amazing! If you need a name that is not listed, just e-mail them and within a day or two, they add that name to the website!