What actual, complete sets could you make out of the various Bionicle parts tubs released? I know that, for example, 6638 had two Kraata containers, and that 6620 makes a Red Vahki.
The list of tubs:
6620 - Ultimate Accessory Set (Red Vahki)
6637 - Ultimate Battle Set (Nuju, Nokama, Red, Green & Blue Vahki)
6638 - Ultimate Creatures Accessory Set (Two Red & Two Blue Vahki, Two Kraata Containers)
8711 - The Ultimate Bionicle Set
8713 - Ultimate Bionicle Accessory Kit (Old little sets like Matoran and Turaga???)
8715 - Bionicle Exclusive Accessories (Vahki???)