In Safari, you can highlight text using traditional click-drag selection method. But there is one more way of highlighting text in Safari. Instead of a single-click to begin the highlighting, use a double-click, hold and then drag. As you drag on, Safari will highlight by word, not by a single character proximate to the cursor.

This makes selecting much easier and more accurate (assuming that you want to select words in their entirety).

While not necessarily groundbreaking, it should be noted that Command - ~ (tilde) will allow you to cycle through all open windows. Command - Shift - ~ (tilde) cycles the windows in reverse order.

OK, most OS X users know that you can use the Spacebar to scroll down a web page, one screen at a time. Very handy. Did you know that you also can use Shift-Spacebar to move back up the page one screen at a time?