If you've had your PSP for a while and are starting to get a little tired of its built-in theme then have a stab at creating your own with Custom Theme Converter.
Sony has kindly developed the app with the necessary resources for building themes for firmware 3. 70. The program itself is pretty straightforward to use, and it's just a case of loading the icons and the bottom of the screen you want to use before using the app to store this new theme on the internal memory.
However, the tricky part is the creation of the icons and buttons themselves, which can grow to become a very laborious process. Custom Theme Converter offers no help on this or even any tips on how to make a good one.
Well, maybe it does, but the instructions are all in Japanese.
Custom Theme Converter offers you a solid platform for creating high quality themes for your PSP.