As has already been posted, hair color, lip pigmentation, and personal taste all factor into which nude lipstick you'll want. That said, you might still want to check out the following three products, especially if you can't pull off super light nudes. I can't.
Velvet Teddy- A pink-beige that is a bit darker than nw20 skin. Matte texture.
Honeylove- Similar to Velvet Teddy, but slightly lighter and pinker. Also matte.
C-thru (Lipglass)- A semi-sheer light, peachy concealer color. Worn alone, this lightens the natural lip color without looking harsh.