There's always been an element of artistry to UI modification. Often it trends towards the functional, but every once in a while it's flat out beautiful to behold. Such is the case with Crow's Super Happy Yellow Butterfly User Interface of Doom and Inner Conflict (aka CSHYBUIODIC.)
It reminds me of the first time I see a visually striking zone like Zangarmarsh or Moonglade. It's so lush and vibrant, it's a pleasure to look at. And she made a darker and brighter version.
Now, butterflies and pretty flowers may not be your gankalicious-pwnage -chucknorris cup of tea, but in a sea of sterile looking UI's this one stands out. You can see the entire screenshot linked in the artist's forum thread. She's not quite done with it and is looking for feedback.