I used to do screen sharing through iChat (Mac to Mac) but this was always a hassle when I was using multiple external monitors (the screen/text was too small and nearly unreadable if the person I was sharing with was on a laptop). There could exist some fix for this but I never found it.

Screenhero handles this much better and I can just share an application (e.g. VIM, Chrome, etc.) and the distortion is minimized. At first I didn't think the multiple mouse feature was that big of a selling point, but I've actually found it quite useful; when working on a remote team you can't physically point that the screen with your finger so the mouse does the job :)