Collaborative tools are on the rise and Sugarbox is one to keep an eye on. In addition to the core screen sharing and multi-user control you'd expect, Sugarbox allows you to record sessions for playback later, offers presentation mode, and live chat (text for now but voice coming soon). Users can mark any web page with corrections in real time through the annotations feature.
Ease of use for collaborators sets the experience apart since there is nothing to download. Simply share the custom link to start a session and your team can join you or use it on your own to record UX notes for your own reference later.
Don't let the beta fool you. I recently combined Sugarbox with Portly for a class and it was a powerhouse. Whether you plan to use it on a team, with clients, or in an educational setting, Sugarbox is one to watch.