Vyew makes short work of sharing images or PowerPoint files. It's also easy to snap a screenshot and share that, or even set up live screen sharing, although the screen updates are a lot choppier than with a software-based presentation tool. Users can chat during a presentation or mark up the screens they're viewing, in real time.
You can also share a Yahoo map in realtime (as you pan and zoom around it), and create a photo show, with a music track, that you can push out to viewers. There are some bonus modules too, including a simple diagrammer (better bet: do a screen share of a Gliffy session), a calendar you can draw on, and a Checkers board.
Compared to the software-based products, the big upside of Vyew is that you can be up and running with it in about thirty seconds, and have people across the country on your presentation in another ten. There's no software download required. That also means it should work on other platforms besides Windows (I didn't try that). And like other online applications, it's free, at least for now.
Downsides: The interface a little clunky, and it is also so garish it distracts from your presentation. And as I mentioned, live screen-sharing is not smooth.
Vyew is worth a bookmark. A lot of people do online presentations rarely, but when they need the capability, they need it badly. Professional screen jockeys might be better served by a more capable, software-based product, but Vyew is a very good tool for the occasional remote presentation.