Navigating elements on web pages with the Tab key is a useful feature in most web browsers, but since the release of Mac OS X Lion the new default behavior in Safari seems to limit what the tab key selects on a page. Here’s how to enable tab key navigation across all actionable elements on a webpage:

From the Safari menu pull down and select “Preferences”

Click on the “Advanced” icon and check the box next to “Press tab to highlight each item on a webpage”

Note the sub-text points out that if you press Option+Tab then you will select only the text input boxes and menu items, which is the default behavior of Safari and Chromes tab key navigation.