Skype competitor Gizmo is rolling out a Flash version of its SIP phone client. GizmoCall works entirely in the browser, much like other Flash-based phones from Ribbit (which was acquired by BT), TringMe, and others. In fact, Gizmo’s in-browser phone comes about a year too late. (But it still beat Skype).
Like Skype, you pay really low rates for calls to regular phones, while PC calls are free. GizmoCall supports video calls as well. And one nice feature is that it can turn any phone number into a link, like this test number.