These are the wallpapers I use on my PSP. I took images I found on the internet and resized them, so don't give me any glory, but I think these all work really well.
I like the mirror's edge on the best. I don't use wallpapers though, because I'm laaaaaaazy. However, the background color does change month by month, which is nice. April is pink. My PSP background is currnetly pink.