Looking for addon: Add $X to cart for free shipping

I offer free shipping over $99. I'd like to see a line in the checkout page that says "Add $X more to your cart to get free shipping". X would be equal to $99-Current value in the cart. If they are already over $99, this would not show up. Is there an add on or something already in zen-cart that can do this?

Thanks!

This might work:

http://www.zen-cart.com/index.php?main_page=product_contrib_info&products_id=394

I haven't used it.

There's another similar mod that also adds a 'Checkout' button to the sidebox.

If you want this function in the header, Shoppingcart/Freeship in Header does that and is fully stylable with CSS. (it also supports multiple languages). Its code is based on Cart Sidebox with Free Shipping Qualifier and Checkout Button Free Shipping Qualifier if you want a sidebox.