The original idea behind doing an Open Full Moon was that it would help give the lodge greater exposure in the local pagan/wiccan community. Unfortunately, even greater public exposure will not increase the local lodge membership unless we can give people a reason to want to join.
Hence, I plan on talking about how there are several Golden Dawn techniques that can be used in a wiccan setting. Such as the Purification and Consecration by Water and Fire, the Lesser Ritual of the Pentagram, and the Middle Pillar ritual. I might mention the use of godforms, and how several keys of Gardnerian Wicca came from Golden Dawn though the route of OTO (Thelema and Aliester Crowley). Or maybe not, depends upon the audience.
Hopefully, it will spark some interest. If nothing else, it makes Alia happy that I am doing a ritual (OFM).
[Updated--June 21, 2013: Link to lodge site changed to current official site.]