Illumination by Daniel Parnell

This one looks really snazzy. It claims to be a true theme system for Windows, with freeform skins and eventually every feature WindowBlinds has. Oh, and it's open source as well. Development is coming along well, it was updated just recently at the end of June.

  • Official Sites
  • Unofficial Sites
  • Screenshots
  • Download Sites

Also see WindowBlinds, eFX, Chroma, CustomEyes, Daya.