OS X has a little known feature that allows you to scroll open windows while they remain in the background. Usually, you discover this feature by accident when you are using an app in one window, hover your cursor over another open app window and scroll your fingers by mistake. You then are shocked when the background window contents move in response to your fingers.
The ability to scroll the content in a window that does not have the focus (is in the background behind the window in which you are working) is available in OS X and many Linux distributions, including Ubuntu. I use this background scrolling all the time when I write. I keep my text editor in the foreground and the web browser in the background. This arrangement allows me to scroll a web page and not have to switch windows when I am done reading and want to type in my text editor again. This background scrolling works with any combination of apps.
One bonus feature is the ability to interact with a web page that is in the background using the command key. If you are reading a page and it has a link, you can open the link in a new tab without losing your focus by holding down the command key and then clicking on the link. This option is useful when you are multitasking and don't want to be slowed down by switching windows. For example, I can stay in my email client and open a few browser windows while I wait for an email attachment to download.
If you have any other OS X tips, please share them in the comments.