I know that with other rescue events I've been to---- I've seen auctions, as well as artwork -- whether be photography, drawing, crafts, jewelry, volunteers would show off their special talents and/or even sell their work. (proceeds going to the rescue)
I've seen at several parties, they would do themes like "spa paws" where the party would include brushing and trimming nails on bunnies. It's gets all the bunnies groomed while people gab and blab.

You already have a fun theme--- Christmas in July, so instead of doing a "White Elephant....errr Bunny??" gift exchange. You could make it a silly or sophisticated party as I have seen both and I enjoyed both. Music, wine, auction, stuff for sell, good food. Just a good time.