Voice Mac has a pretty basic set-up—you have a filterable list of all your contacts (which can either be populated by Google, which includes your contacts and numbers from your sent and received call list that aren't in your contacts), or just your local Address Book on your Mac. You can call any of your contacts, choose which phone to ring, and even bring up a separate window for SMS, like an IM—complete with dock icon badges and Growl notifications.
In addition, you can also bring up a separate window to view your call history, SMS history, and voicemails. It even has it's own reverse lookup function, complete with Google Maps integration, to show you where that unknown number is calling from(and possibly who it is).
Voice Mac is a free download, Mac only. Thanks, Jamie!
