.element-invisible {
  position: absolute !important;
  height: 1px; width: 1px; 
  overflow: hidden;
  clip: rect(1px 1px 1px 1px); /* IE6, IE7 */
  clip: rect(1px, 1px, 1px, 1px);
}

Full credit to Jonathan Snook. His article and reasoning here:
http://snook.ca/archives/html_and_css/hiding-content-for-accessibility