Gizmo Project makes all VoIP to landline calls free. Forever.
Frustrated that Skype doesn't allow free international calls from international locations? Gizmo does, free! You can even buy a Call in line for $3 a month so your friend can call you from their landline. Available to Window, Mac, and Linux users! The only catch to this I've found so far is that the person on the other end only needs to be registered with Gizmo, but thats a small effort for free global calls, plus Gizmo just has better features than Skype.