[Jach]

Application-independent zoom is such a nice feature. I've been keeping a zombie version of compiz (formerly beryl) on linux working for years, mainly because I love my wobbly windows and desktop cube, but it's long had two features great for screen sharing purposes too: the zooming like you mention (have it bound to meta+scroll wheel) and drawing annotations (alt+meta+left click for free drawing, there's also eraser, erase all, straight lines, and filled rects/ellipses).