If you meet with employees, coworkers, partners, or vendors remotely, virtual meeting services can make your meetings much much more productive.
There are several platforms for virtual meetings but the big three are WebEx, Windows NetMeeting, and GoToMeeting.
GoToMeeting is probably the strongest for a few reasons:
1) Incredibly fast meeting setup/configuration and integration with Outlook and IM platforms to start meetings
2) Free voice conferencing
3) Flat pricing — unlimited meetings, as long as you’re under 10 attendess
4) The usual collaborative and management features like screen sharing, meeting recording, etc.
GoToMeeting is offering a Free Trial + $10 Off!

WebEx has been around for longer and has many of the same features. To me, it feels more clunky, but it still works fairly well.
Windows NetMeeting is barely worth the hard drive space. Microsoft is discontinuing it when Vista ships and is moving to something called Office Live Meeting Space.