I now own most of Stargate SG-1 on DVD (everything up to series 7 so far). One of the reasons I wanted to buy it was to fill in the gaps on some of the episodes I missed. SG-1 features many multi-episode story arcs and missing one in the middle can be confusing. So just for reference for anyone who might be interested, here are some lists of episodes for some of the more important story arcs.

Some of the episodes are only debatably part of the story arc. For example “The Torment of Tantalus” is the first reference to the great alliance of which the Asgard were a part even though it has no mention of the Asgard themselves.

Asgard

Series	Episode	Title
SG-1	1x09	Thor’s Hammer
SG-1	1x10	The Torment of Tantalus
SG-1	2x06	Thor’s Chariot
SG-1	2x15	The Fifth Race
SG-1	3x03	Fair Game
SG-1	3x22	Nemesis
SG-1	4x01	Small Victories
SG-1	5x05	Red Sky
SG-1	5x22	Revelations
SG-1	6x17	Disclosure
SG-1	6x11	Prometheus
SG-1	6x12	Unnatural Selection
SG-1	7x03	Fragile Balance

Tok’ra

Series	Episode	Title
SG-1	2x02	In the Line of Duty
SG-1	2x11	The Tok’ra (Part 1)
SG-1	2x12	The Tok’ra (Part 2)
SG-1	3x12	Jolinar’s Memories (Part 1)
SG-1	3x13	Jolinar’s Memories (Part 2)
SG-1	4x03	Upgrades
SG-1	4x05	Divide and Conquer
SG-1	4x12	Tangent
SG-1	4x22	Exodus
SG-1	5x01	Enemies
SG-1	5x02	Threshold
SG-1	5x15	Summit
SG-1	5x16	Last Stand
SG-1	6x09	Allegiance

Apophis and Klorel

Series	Episode	Title
SG-1	1x01	Children of the Gods
SG-1	1x07	The Nox
SG-1	1x15	Cor-ai
SG-1	1x21	Politics
SG-1	2x01	Within the Serpent’s Grasp
SG-1	2x02	The Serpent’s Lair
SG-1	2x08	Family
SG-1	2x09	Secrets
SG-1	3x09	Rules of Engagement
SG-1	3x15	Pretense
SG-1	4x14	The Serpent’s Venom
SG-1	4x22	Exodus
SG-1	5x01	Enemies
SG-1	5x02	Threshold

Tollan

Series	Episode	Title
SG-1	1x07	The Nox
SG-1	1x16	Enigma
SG-1	3x15	Pretense
SG-1	3x18	Shades of Grey