Just hide it in the browser when they mouseover the link ?
3 ways to do this, pick your favorite:
javascript
( slow and not all browsers will pay attention )
base64_encode
( easy to decode )
convert all links to form submit buttons with post methods
( probably the hardest of the 3 to get around )
Hide it in the location bar in the url? Only the 2nd or 3rd method would do this. ( I recommend the 3rd )