A black skin seems to brighten it up. Bold or heavier fonts make a difference.
I went back to my PRS-600 after using a pearl display and after a few days it stopped bothering me. I didn't use a skin or heavier fonts, I just realized it was better than good enough.
I now have a 350 and a T1 but I use my 600 for reading on the balcony.
Strangely enough I find the 600 interface much more functional. The 350 and 650 both skip around randomly on occasion, the T1 is missing the alphabetic navigation on the side and the search and delete functions seem to only work when they want to.
Oh well Sony giveth and Sony taketh away.