Available in both full-featured Pro flavors and a stripped-down Free variety, Citrix-owned GoToMeeting has a conferencing solution for just about everyone. The simple GoToMeeting Free lets you video chat and share files with up to three participants (a browser-based solution for Google Chrome only, no registration required).
The beefier Pro is a full-fledged conferencing system that supports up to 100 viewers. Features include full screen sharing, collaborative on-screen editing, text chat, and the ability to dial in for audio via phone.
Platforms: web (Free only), Windows, Mac, iOS, Android
Pricing: free (up to 3 participants) to $59 per organizer/month (up to 100 participants)