The builders of Gizmo Project have just unveiled Gizmo Call, which allows you to make phone calls from your browser, using a Flash-based mini-app. You get five minutes a day of free calls to any phone line, along with unlimited free calls to users of Google Talk, Windows Live, Gizmo Project and any other SIP service.
It seems that plugin is only available for Windows and Mac. No Linux version 🙁
I’m not sure … But I suspect that it’s just a a matter of time 🙂