Hula is a traditional Hawaiian dance. In case you don't know it, check out this video:
Hula dancing can be a fun add on for your Hawaiian luau party. You can even make it into a contest. Just get a few willing participants and let them take turns dancing the hula!
You can also include other guests in the fun, not just as spectators, but also as honorary judges. Deal out a bunch of boards with numbers from 1-10 and let them judge the contest!