One thing I love about OS X is that no matter how long I use it, I'm often surprised by something that I didn't expect to find. That was the situation last week when i was using Apple's Preview app in OS X 10.8 Mountain Lion to resize an image, and found myself looking at a part of the image through a magnifying loupe.
The loupe moves wherever your cursor is, and provides a nice magnified view of whatever you happen to be pointing at. While images might appear a bit pixelated within the confines of the loupe, it's a perfect way to get a closeup view of details that you might otherwise miss.
I accidentally made the loupe appear when I was trying to press the "1" key on my keyboard and pressed the "grave accent / tilde" key instead. It's the key just above
