The save file created by PS1 games is actually a generic memory card file rather than a save associated with a specific game, so it supports multiple games (even if you put them in a differently named folder, the game still knows to look for saves in that memory card file). You can use that one SCUS94476 folder for ALL your ps1 games, it doesnt overwrite previous saves since its based on slots like a real memory card.
So I think it deserves a memory card theme rather than be game specific. Ive only seen backgrounds for games so far, I think people should share their memorycard/psx themed files.
This is a background image I made, it uses alpha transparency, so it looks pretty cool in the PSP with a moving background.