It is because the “flaw” within Mac OS X, this has made Divvy one of the awesome Mac app. This morning after I saw people recommend the app and immediately tried it out and I love it.
The key feature is to resize the app windows to according to grid. To a perfectionist, I couldn’t tolerate windows to be at ‘restore’ state scattered around my desktop, where it seem too messy for me. So usually I have it to be maximize or at the well arrange state. As you know, Mac OS X is totally dumb on windows resizing, even the simplest snap-to-edge isn’t there.
Before that, I have tweak my windows maximize button with RightZoom. The Divvy just making it better, it let me have the full control of my windows. It can be chosen to stay at the system tray or even fully hidden, trigger only with shortcut key.
They also have for Windows version, but I think I quite use to my Windows 7 already.