On the Web: Supersize Me

2. More Advanced Cross-Selling: If you're already doing the basics, step up to the next level by showing multiple types of cross-sells on the same page. These can include product groupings like "category top sellers" and "people who viewed this product eventually bought these." You also can have your merchandiser select complementary products (filters for a water purifier, for example). Recommendation engines like RichRelevance, Certona and MyBuys are great at increasing average order size.