First Edition

Blood Bowl (First Edition)
Blood Bowl (First Edition): Death Zone
Blood Bowl (First Edition): Skaven Team

Second Edition

Blood Bowl (Second Edition)
Blood Bowl (Second Edition): Elves, Dwarfs and Dungeonbowl takes the game underground and includes figures for two teams: one Dwarf and one Elf.
Blood Bowl Star Players expands the game with the creation of new star players, a simple campaign system and new races.
Blood Bowl Companion introduces a lot of new rules as well as the official NAF game variant.

Third Edition

Blood Bowl (Third Edition)
Blood Bowl: DeathZone
Blood Bowl: Living Rulebook

Note: I am fairly certain that this list of Blood Bowl games is not complete. I am only familiar with the second edition. Perhaps someone else can flesh out this list and explain the differences between editions. Thanks - catnthehat.

This Geeklist describes the development of Blood Bowl through the different editions.