Yikes. 2.5 ounces of elderflower to 1 ounce of Gin? Are you sure these proportions aren't reversed? That would be one sweet cocktail (and not in a good way).
Uhh... Nobody mentioned caper berries? Awesome... (If, of course, you like capers.)
Chopin's "CEO" Martini promotion came up with some awesome ideas, but they're not posted publicly anywhere. Fortunately, I kept a copy and made a PDF of it. Anyone interested, just send me a direct message.