Resolution for a 2D html5 canvas game?

Resolution for a 2D html5 canvas game?

I am finding it hard to decide what resolution (canvas size) to use for a html5 canvas game which I am about to start working on.

I know that ideally it should support almost any size, within reason, but that it really difficult to do in practice, so for now I want to pick a certain size and live with it.

The size I am tending towards is 800x500 -- as the aspect ratio supports widescreen monitors well, and doubing up to 1600x1000 would make it a decent size for people running resolution 1600x1200, 1920x1440 (etc) on their lcd monitors.

What I don't know is what are good sizes for mobile devices.

Any and all advice will be appreciated!