Also on the WoW Forums:
http://us.battle.net/forums/en/wow/topic/20749748615
With the updates made to the flight path map in the patch today, I had what could be a fun idea for a couple new engineering items. The goal here is not to make travel super easy in general (a'la mass summon), but rather to supplement the current systems (flight paths/summoning stones).
Flight Master's Recoordinater X-Treme
Use: Set up a flight path coordinator at your above-ground location. Party and raid members can purchase flight paths to and from that location for 5 minutes (30 minute cooldown).
The game basically creates a "Dummy" flightmaster at your location that people can fly to/from. It will take them on the normal flight path pattern to the nearest point where they would usually drop them, then veer the mount out toward you for a nominal (1 flight path) fee. When the flightmaster leaves, people en route still go there, but others can no longer choose it.
Also for the discerning engineer:
Potent Portal Potable
Use: Has a good chance of summoning one party or raid member to your location and consumes the item (60 minute cooldown). Cooldown is shared by similar consumables.
This will help you get that one extra person to you for summoning quickly... most of the time. It can also backfire, like any good engineering item can. Can adjust to 1/day instead if that proves too useful. The flight master can be a goblin engineering item (since it costs money), while the potable is gnomish with a chance to accidentally summon a level-appropriate demon instead.