I need to share my screen operations with others in a LAN. The watcher number may reach to 100.
I know netmeeting is OK. But it's too old.
I want a better/newer software for destop sharing. Free softwae or Opensource software will be better for me, since $ 
xcloudy,
Have you tried Mikogo? http://www.mikogo.com
It is completely free and you can use it for free screen sharing meetings and share any screen content in real time and true color quality. You can then switch presenter so everybody can look at another person's screen. If you need remote support, there is a remote keyboard and mouse control feature included. With the Skype Extra you can talk and share your screen for free.
There is a recent news article about Mikogo here on the Webinar News Blog
If you are interested and are looking for more info, you are welcome to contact me: andrew(at)mikogo.com
Andrew I'd recommend you check out Glance. I work for Glance Networks and we have many customers in your exact situation who use Glance. It's incredibly simple and easy to use - just a few clicks are necessary to set it up, and it works cross-platform with up to 100 viewers as well. I'd definitely check us out and give it a try! Thank you for both your recommendation. I would definitely try them.
But both of the two requires internet connection, while my environment is LAN. So I'd like to welcome someone to recommend a software for LAN desktop sharing, no need of internet connection. Thanks.
Do you really want to share the desktop to 100 of users or just stream a video of what you are doing?
If you really want to share your desktop with 100 of users, I think it will be a nightmarish experience of controlling the mouse and happenings of screen!!
I found another web meeting software located in http://dimdim.com
It seems good. Hey buddy, you can use VNC for this purpose, but its not free. But its a very good software.
Take a look at TightVNC. It's free (& open source) and appears to do what do you want. I'm afraid I haven't yet used it myself, so can't give any guarantees. VNC is a P2P software, it's not suitable for meeting that have lot's of panticipants.
