I play some left-hand-only stuff a la Garry Moore with lots of open strings (yeah, wave to the audience), and then for contrast some heavily muted shreds a la Paul Gilbert, throw in an arpeggio or two, and an all-the-way-up scale. So far it's all improvised, but i like to add something like the Pink Panther theme, or some gipsy-sounding Brahms. Oh, yeah, the Crossroads duel is kinda effective, as well. Not too much 2 hand tapping, if any, as it's got to be the cheapest impressing technique, at least in my oppinion, and I've heard quite a few non-musicians aggree.