Call center workers, this one's for you. Ovolab's Phlink is a powerful application to manage all your incoming and outgoing calls.
Once your phone is connected to Phlink via USB, the application will log in all calls that go through it. You can easily keep recordings of all voicemail and transfer calls to the phone numbers of your choice. Phlink integrates Spotlight search to find any call quickly. Calls can be kept in smart lists, tagged and labeled.
That's not the only Apple application that Phlink works with. The application will recognize your contacts stored in Address Book, and will bring up a little notification with their details when they call you up.
I didn't really like that the disk image came unbundled and with so many elements, something you get less and less in Mac apps. However, Phlink also comes with a very handy set of widgets, so you can manage your calls straight from your Dashboard.
One last point, Phlink costs around $149, so it's obviously aimed at professionals rather than personal users.
Expensive, yet an intuitive way to manage calls. The widgets are also an added plus.