The Deeprun Tram
The Deeprun Tram links the Dwarven city of Ironforge and the Human city of Stormwind. It allows easier access to the auction house, trainers and vendors for each race. The system is made up of two trams that follow the tram circuit roughly every 2 minutes. The tram is an exceptionally cheap method of travel between the two cities. It enables the player to make the trip with no cost at all, same as the boats or zeppelins.
Should you use the tram over flying? It’s a matter of personal preference. The first time you go between Stormwind and Ironforge you’ll more than likely need to take the tram since the path between the two cities is through two level 50-60 zones. After you obtain the flight points of both Ironforge and Stormwind the option to fly between the cities is given. Neither way is technically faster since the tram has the variables of when the tram arrives along with the loading/walking times while the flight path is always the same. The tram is also free but at the same time requires a good deal of effort to take while flying is on demand and the cost is a non-factor once you gain a few levels.
With the Burning Crusade came new forms of public transportation. In Shattarath City, players can find portals to each of the major racial cities. This allows easier access to trainers which are not available in the Outlands. The cities that can be reached by portal from Shattarath are: Exodar, Darnassus, Stormwind and Ironforge for the Alliance and Silvermoon City, Orgrimmar, Thunder Bluff and the Undercity for the Horde.
Two translocation orbs can be found in the game. They are connected and enable the user to travel between them. The first is found in a side hall in the Ruins of Lordaeron. The second is found in Sunfury Spire in Silvermoon City. Right-clicking on either of these will transport you to the other one.
Private transportation in WoW is broken up into 4 basic modes: Mounts, Hearthstones, Spell Based (Teleportation, Portals, Summoning) and Travel Forms.