I wonder why nobody speaks about http://teamviewer.com? I tried it and in deed just works like a charm. No need for any registration either, just download and run it directly. This took me something like 2 minutes to run it. You even not only share the screen but has also a full remote access. Yeah, it even works on any kind of OS (Win, Mac, Linux, Android, iOS).

What is so special about this new screen sharing startup which hasn't been solved already by other projects? I would even claim that Teamviewer does pretty much nails the problem of screen sharing.

[Disclaimer: I am not affiliated with teamviewer in any sense.]