Right now I am doing buttons and some graphics like this:
Put the buttons in a sprite image.
<a class="button" href="mylink.aspx"><span>Button text</span></a>
background: url(mybuttonimg) 0px 0px no-repeat;
background-position: 0px -30px;
However I found out that positioning the text off the page will hurt our Google rankings.
And we still want the button text, probably as an image alt tag