I have been using Countdown maker for the past 3 years and it works great. It is a mac only program, however. It has a straight-forward interface and exports quicktime formated media. If you are creating video or still images and want to add a countdown, this is the program to use. My workflow is to create the largest countdown number size possible within the interface and then export as an animation file. The animation file contains the alpha channel. I then take that file into After Effects or Premier Pro and add as an overlay. Using 3D Extruder, I can even extrude the timer.