FreePlay released TIFF Font Hack Installer v0.1 for PSP firmware 2.7-2.80 (2.0, 2.01, 2.5, and 2.6). Originally created by FreePlay, TeamOverload, and Skylark, the font hack enables PSP users to change the fonts on the PSP's home XMB screen.

Other things you can play around with: italic, bold, shadow, and other style options for fonts.

FreePlay says its one drawback is that you have to manually edit and fix your registry using some other tools they made. But they are working on ironing out this kink.

To install:
Copy the program to PSPPHOTO on your Memory Stick.

To run the program:
Highlight the 'fonthack' folder from your PSP's Photo menu, then press Start.

To modify your registry:

1. Use the parsedreg/fixupdreg package (included in the download file). Extract the ZIP file to your computer.
2. Run the Font Hack Installer, and press Cross to copy your registry to your Memory Stick.
3. Copy the system.dreg and system.ireg files from your Memory Stick to the parsedreg/fixupdreg folder.
4. Open system.dreg (NOT system.ireg) in a hex editor. Replace every instance of "flash0:/font" with "ms0:/fontmod". Save the file.
5. Double-click fixupdreg3.exe . It should pop up a window that closes automatically. Your registry should now be fixed, assuming everything went well.
6. Copy system.dreg and system.ireg back from the parsedreg/fixupdreg folder to where you found them on your Memory Stick.
7. Run the Font Hack Installer again, and press Circle to install your modified registry.