OK, this isn't a travel gear item that you're going to take very far, but I have to admit I got pretty darn excited when this Mionetto IL Party to Go showed up at my house. It's basically two bottles of Prosecco in a plastic tub for ice, with a custom top for the tops of the bottles to poke through. It even comes with some plastic champagne flutes.
The Mionetto IL party bucket is a bargain too, retailing for $19.99 (not including ice of course). See more about it at ILSparkling.com.