You should be able to do this with the keyup event. To be specific, event.target should point at the selected element and event.target.href will give you the href-value of that element. See mdn for more information.
The following code is jQuery, but apart from the boilerplate code, the rest is the same in pure javascript. This is a keyup handler that is bound to every link tag.
$('a').on( 'keyup', function( e ) {
if( e.which == 9 ) {
console.log( e.target.href );
}
} );
jsFiddle: http://jsfiddle.net/4PqUF/