Objective Decision released a free update to their oddly-named flagship product Contactizer. A powerful, Sync Services-savvy personal information manager (PIM) application, Contactizer 3.6 comes in Pro and Express flavors depending on your needs.
I used an earlier version of Contactizer last year and was impressed with its power, although I did run into issues with how it synced with iCal and Address Book. One of the best features from my viewpoint was the ability to track tasks throughout an entire project using the Project Manager mode (see screenshot above). Contactizer also did a great job of handling mail merges, and I found the way that it integrated email information into my contact list to be very helpful.
The update includes a Leopard-only Cover Flow mode that displays contacts as business cards, an improved sync system that works with multiple calendars, a quick entry panel for tasks, and a number of other user interface improvements.
Contactizer is a Universal Binary application which requires Mac OS X 10.4.8 or better. You can download a 30-day free trial, or purchase Contactizer Pro for $119 (Express is $59.90).