Mikogo is a free software for screen sharing and online meetings. Mikogo also offers Skype extra tool.
Mikogo allows to share your desktop up to 10 participants simultaneously. To start a meeting download the software and create a meeting. Now invite all your participants, you will be notified when the participants join your meeting. When they join they will immediately see your desktop. You can also switch presenters in the meeting, useful if collaborators wants to have a meeting. It also allows to transfer files between users.