Drupal 7- "Users who bought this also bought that" module
There are two modules available for Ubercart; the first one is Ubercart Products Recommender which provides a View for:


  Users who ordered this product also ordered.


The second is easyrec for ubercart, which provides a block called:


  other users also bought


Either one should be fine for what you want, and both have a stable Drupal 7 version available.