Two of the most useful features of Windows 7 are Aero Snap and Aero Shake. The first feature enables you to quickly resize program windows by dragging them to one of the four edges of your screen, while the second makes it possible to easily minimize all open windows by grabbing on and shaking left and right with your mouse. By installing iSnap, you can bring these handy features to your Mac.
Should you decide that you do not want to use both of these features, you can choose which of them you would like to enable. If you would prefer that your app windows were not automatically resized for you, for example, you may choose to disable the iSnap feature while retaining iShake. If you need to temporarily disable either of these features, this can be achieved using keyboard shortcuts.
If you find that you do not get on with the way iSnap and iShake work by default, you have the option of use the menu bar to choose what you would like to do with windows. There are also a number of keyboard shortcuts that can be used to manipulate windows without the need to more your fingers from the keyboard.
Some users have reported issues when used under Lion as well as compatibility problems with Microsoft Office 2011, but it is good idea to take the app for a test drive to see if it could work for you. Keep checking back for updates to see if any of the existing bugs have been ironed out.
A great free utility that is slightly marred by a lack of support for some apps but still worth checking out.