Surely the Wraith have power sources even though their ships are partly biological, if we could down enough wraith darts we could incorporate their power systems into Atlantis therefore providing slightly more power to the city. What would be quite cool is just installing the asgard teleportation device and have it linked to the life signs detector so that when a Wraith is detected in Atlantis then the teleporter sends it into the atmosphere. Simple way od dealing with them easily. Or straight into the ocean. Either way they probably die unless they happen to have just fed upon a few hundred people so they then are invincible.