Most people these days will be familiar with the webinar, where someone can effectively broadcast their message to a bunch of attendees. That ‘bunch’ could be from 2 to 200+ people from all parts of the world, add VOIP to the mix and you have a complete IP based method of sharing your idea, product announcement, training session – the list is endless.
In addition to the webinar approach you have a very close cousin that allows a straight peer to peer screen sharing arrangement, it is often employed in helpdesks or anyone doing any sort of software/hardware support. There is some cross over here.
Some of these apps you certainly pay for, although in their defence you are getting features that a mid to large enterprise would expect to use, like the ability to track attendees, recording webcasts etc. For the majority of use cases though there has appeared some very cost effective options, so I thought I would share with you some of the free solutions out there.
Yugma
Has both a paid and free version available, the free version lacks things like, sharing mouse & keyboard, session recording, multiple monitor support and control hand-over (there are more).
That said, the paid version which adds all the good stuff starts at a measly 15 bucks.
Performance was solid with screen updates working within a tolerable range, this is very important as lag will drive you nuts.
Find out more here.
http://www.yugma.com/
Microsoft SharedView
From the folks in Redmond comes SharedView. It is totally free and allows you to collaborate with up to 15 people. You can hand over control, send out files and hand outs and has some level of integration with MS Office and Instant Messenger.
Performance was just OK. Installing on Windows 7 is also a pain, I had to edit the .MSI with Orca to change the entries in the ControlCondition table. 
Orca can be found on your local system if your a Visual Studio 2008 user, go here:
C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bin\
Otherwise download it from Microsoft here (its part of the Microsoft Windows SDK)
Get the SharedView installer below:
http://www.sharedview.com/
Skype 4.1 Beta
I was hunting around the Skype site for information on its recently released “Skype for SIP” release so I could experiment adding a Skype gateway to our current VOIP setup. I came upon the release notes for the 4.1 beta, it now supports screen sharing!
The notes add its only one to one sharing for now and its only in a single direction – you cant simultaneously see each others screens.
Haven’t tried it out yet but it sounds promising and given the massive size of Skype’s network I am hoping lag is at an absolute minimum.
More to come on this topic I would say.