Macintosh applications always seem to take cuteness right to the edge. Playing around with my recently acquired Newton, I was highly surprised by the deletion effect, where scribbling an item out causes it to disappear in a puff of smoke. Now, I'd just about got over this effect on my 12" PowerBook G4 -- I certainly didn't expect to see it in use on a low powered piece of kit from about 10 years ago. Somehow however, they never seem to actually cross the line into excessive, leaving the user wanting more every time.
Another example of this is Apple's iChat which I finally got around to trying for the first time ever today. I'll admit that I thought I would hate it. But, after no more than 5 minutes, I had fallen in love with this somewhat quirky user interface. The only problem I have now it is that it runs on AIM!