Free Gems: BootXChanger
For a while, I was searching for a way to change the startup image. In OS 10.4, Apple indicated they were onto us hackers by requiring more than a simple switch of a PNG. Up until now, I only found Terminal-based solutions that scared the dickens out of me. BootXChanger makes it too easy by letting you switch the image through a single drag and drop. Now, you can impress your hipster friends with the 80s Apple logo, or come up with something more unique like this.
via Smoking Apples

Love it! I now have a happy mac for my boot screen!