Yes indeed. Slow handclapping also has the particular function of indicating impatience, e.g. when a concert is late starting (I've seen it being done in Flanders, so it's not just an English-language area thing). But applause at classical concerts in France and Italy which evolves into rhythmic clapping indicates that the audience is calling for an encore.

Eric Clapton reportedly got the name "slowhand" from being repeatedly slow-handclapped when he broke guitar strings and spent "too long" fitting and tuning replacement strings.

I on the other hand am engaged in a fruitless search for polite gestures for use while driving. I'd like to be able to indicate "sorry", e.g. when I unintentionally flash my lights at the car in front instead of switching on the windscreen wipers, but oddly enough the need for such a gesture doesn't seem to be widely perceived.