Doorway Card in general:
Alternate Universe Door Allows 'alternate reality' cards
Bajoran Wormhole Allows travel to/from Gamma Quadrant
Bajoran Wormhole: Mirror Universe Allows travel from the Mirror Universe
Barzan Wormhole Allows travel to Delta Quadrant.
Battle Bridge Door Creates Battle Bridge Side Deck
Q's Tent Creates Q's Tent Side Deck
Q-Flash Creates Q-Continuum Side Deck
Space-Time Portal Allows 'alternate reality' cards
Storage Compartment Door Creates Tribble Side Deck
Temporal Micro-Wormhole Allows 'alternate reality' cards
Dyson Sphere Door Creates Dilemma Side Deck

Note: Dyson Sphere Door (used to create the Dilemma Side Deck) is a virtual card by the Continuing Committee and was not released by Decipher in any expanion or printed form. The card is available for free, for you to print, through their website.