GizmoCall: Make Calls From the Browser, My Friend
Gizmo, a VOIP service, is now available through your browser using a tiny Flash plugin. It requires a quick install and some configuration, but after that you can make video and voice calls to Gizmo users and some POTS phones.
Looks like you need a login to taste the magic, so head over to to get it and then give it a go.
Gizmo, now making browser based phone calls [GigaOm]