I have a really small house, so the closets are small. I took the doors off and on my DD's closet I got the really long curtains from IKEA and for my DS's I used a shower curtain with an underwater theme to match his room.
It's not really my thing but their friends love it and it makes it much easier to see and get to everything.
I know Pottery Barn Kids had the hanging beads for boys with a fish pattern on it a while back.