I'm in the process of putting OpenAtria.com online. The basics of the Aegir SaaS implementation are in place, but there's lots of place for enhancing Ubercart with some contrib modules. I've just performed a thorough read through the 386 e-commerce modules liusted on drupal.org as of this morning. I'll categorize them here, and then look to prioritize some.
Discounts/coupons/pricing:
http://drupal.org/project/uc_coupon
http://drupal.org/project/uc_discounts_alt
http://drupal.org/project/uc_discount
http://drupal.org/project/uc_multi_coupon
