ShiftIt for Mac lets you use keyboard shortcuts to quickly adjust window size and position, and manage your screen like you want to. This utility gives you a flexibility that's been missing from the window management options on your Mac, and makes it more convenient than ever to work with multiple windows at once. The downside is that you'll also need to install a different operating system on your computer.
The program is accessible from the toolbar on the top right of your screen. Clicking it opens a drop-down menu that you can use to view hot keys or manipulate windows directly from the menu. Options for window movement include Align Right or Left, Top or Bottom, and Next Screen. There are also options under Preferences for showing the app icon in the menu bar, opening the program at log-in, and setting new hot keys. Additionally, you can adjust the anchors that define the margins of the screen so that the aligned windows appear where you want them, and you can set values for the percent of the window or the percent of the screen you'd like the window to occupy.
In order to use ShiftIt for Mac, you have to install the XQuartz operating system. The app sends you to a site that guides you through the process, and then you can finish installing the software, itself. While this doesn't change much about the way your computer runs, it still can be a drawback, since you may not want to make such a substantial change to your machine for the relatively small convenience the app provides. The program is free, and it does deliver on the features it promises, but you'll have to evaluate whether it's worth it to install a new operating system to get these types of conveniences.