A friend recently asked if it was possible to change the default color of highlighted text in OS X. He is working on a research project, and frequently needs to highlight text, especially in Safari. The standard basic grey color of highlighted text in OS X made it difficult to find highlighted text on the screen.
Fortunately, it is very easy to change the default color of highlighted text. Simply open System Preferences (found by clicking on the Apple icon in the upper left corner of the screen), then click on the Appearance button. In the Appearance pane, you will see a drop-down menu for Highlight Color. You can choose from several options, or create your own color.