Go To Meeting on Ubuntu: Possible, and if not, which alternative?

OpenMeetings

Openmeetings provides video conferencing, instant messaging, white board, collaborative document editing and other groupware tools using API functions of the Red5 Streaming Server for Remoting and Streaming.

Mikogo

Mikogo is a desktop sharing tool full of features to assist you in conducting the perfect online meeting or web conference. Take advantage of the opportunity to share any screen content or application over the Internet in true color quality with up to 25 participants simultaneously, while still sitting at your desk.

Yugma

Yugma free web conferencing allows anyone, anywhere to instantly share their desktop and ideas online with others. To start hosting your own meetings, sign up today for FREE. Your Yugma Free web conferencing account allows you to invite up to 1 attendees with 30 minutes meeting limitations.

I would recommend Teamviewer. It's free and available on all devices. Or Google chrome remote connection for a bit more stability.

Yes, now it's possible run GoToMeeting on Ubuntu: there is a new HTML5 version, which runs fine under Chrome (tested in 14.04 and 16.04). No need to use Phone for audio.

Open it at:

https://app.gotomeeting.com

Or if you want to directly open the meeting using the ID:

https://app.gotomeeting.com/index.html?meetingid=<id>

Then you can create a Web App in Chrome, clicking in the sandwich icon, then More Tools > Create application shortcuts.

Update: According @cr8ivecodesmith, the web client now supports hosting meetings/webminars!