Clothes storage bags

I use a soft-sided bag similar to the ones you use for shopping when you don't want to use the plastic grocery bags. Because they are soft, they conform to any compartment configuration.

I also have a shoe-organizer/hanger similar to the one in Meryl and Me's link, only narrower. It's ideal for socks and undies. Pop a Chinese food take-out container in one compartment and you have a little catch-all drawer.