EDH with two teams of 3.
EDH with six roles that have special missions.
Canadian Highlander
commons only
intended to be unsolvable, this format requires both players to agree to battle for three turns at a time
Modified life totals and banlist
Commander where the general must be Standard-legal
Open a pack (don't look) and shuffle in 15 lands.
Casual Formats from the mothership
Similar to Commander but played with 50-card decks. No cards with casting cost greater than 3 are used.
Players prepare decklists of seven or fewer cards and games are deterministic.
The game has been played weekly on mtgsalvation (with a few interludes) since 2005.