I made a cool web browser (using the Safari WebKit) that imitates the look-and-feel of Windows codename "Longhorn". It is a copy of the Glass part of Aero, the next Gen UI - using transparency to great effect. It's still a work in progress and downloads only available to private testers (mail me for details), although hopefully I'll have a public release up later today. This is my first app I've ever coded in Obj-C - I'm usually a RealBasic man. Check the photo for more info.