Would be great having upsells or related products. For example, I'll sell sport nutrition products in my store, so I would love to have something at the cart showing related products. Usecase: You added to your cart some sweet&salty energy bars, and below, appears related products as isotonic gels, or recovery shake. In that way "helping" users see more products and increase the average ticket. Having added just 2 gels, and an upsell option (quite soft, not intrusive) appears asking you prefer having the whole 12 pack that gives you 10+2 free gels.