Gizmo5
Gizmo5's interface is compact and rectangular, with tabs on the top just below the Menu bar and a series of ancillary commands like Chat and Add Contact available at the bottom. There are very few differences between Gizmo's design and its biggest competitor's. A little originality could've gone a long way here. Also similar to Skype, Gizmo provides free VoIP for computer-to-computer voice chatting as well as text chatting. It also allows for computer-to-telephone voice chatting for both mobile phones and landlines. It has one feature that Skype lacks: it lets you conference call with multiple PCs by entering in a random, shared number. Overall, the sound clarity and quality was excellent, with no lagging nor echoing. Gizmo also says it provides asymmetrical chat-client VoIP, so you can use Gizmo and your headset to talk to somebody on Windows Live or Google Talk. I couldn't get that feature to work, but it's a smart idea and hope it gets debugged soon.
