The first improvement to the site was a popup in the basket for crossells. There are a few nice features included:
It was built upon the crossell functionality within the product section of the admin.
The text is all contained in a static block making it easily editable from within the admin.
If there are no products assigned as crossells the popup will not appear.
If you add a product to the cart from the popup the page will reload and the popup will reappear without the item you have chosen.
The result is a great addition to the site that makes it easier for the customer to view and add to the basket the crossells that are on offer and adds additional sales to an order that might have been missed previously.