Working with multiple windows open can soon become a total nightmare especially when it involves resizing windows to a manageable size.
TwoUp allows you to quickly position a window to fill exactly half the screen via the status menu bar or with configurable system-wide shortcuts (hotkeys). It's very simple to use. Simply select from the menu bar which way you want the window to be move - i.e. left, right, up and down. You may find however that you have to enable access to third party applications in your Universal Access preferences to enable TwoUp to work properly.
TwoUp is useful if you want to split your desktop into two working spaces. For example, you could have Parallels fill up one half of the screen and OS X the other. It's definitely quicker than having to manually resize windows yourself although its far from an essential application. It wouldn't take that much longer to do the resizing yourself.
TwoUp is a simple app that will of use to any Mac user who is constantly working between different windows and soon finds themselves overwhelmed.