Post your abstract wallpapers

While we're all updating, I want to see a nice collection of simple, yet beautiful wallpapers for my phone.
And i'm not talking about the stuff we saw in demonstrations, I want the pretty ones.

  • few colours
  • not cluttered
  • smooth.

for example:

Itxa53z_medium

via i.imgur.com

Also: is there an optimal resolution for those new kid of wallpapers?