How do I hide anchor text without hiding the anchor?

Try

 a{
    line-height: 0; 
    font-size: 0;
    color: transparent; 
 }

The color: transparent; covers an issue with Webkit browsers still displaying 1px of the text.

Wrap the text in a span and set visibility:hidden; Visibility hidden will hide the element but it will still take up the same space on the page (conversely display: none removes it from the page as well).

a { text-indent:-9999px; }

Tends to work well from my exprience.