Adobe CS: Acrobat Connect
When Adobe acquired Macromedia we got a great technology called Breeze. Breeze has been rebranded Acrobat Connect and Acrobat Connect Professional. Acrobat Connect allows you to host online meetings with up to 15 people at a time 24 hours a day. The beauty of Acrobat Connect is that it's based on Flash technology which means that you can be assured that 98% of your meeting participants will be able to participate in your meetings without having to download anything first. Although it's called Acrobat Connect you can use this technology to share your screen/desktop and show any kind of application including PowerPoint presentations. Acrobat Connect is a hosted service and therefore there is a monthly fee. You can signup for a free trial account to try it out.