In Barsaive and Eberron they have Sky Ships, but on Lemuria they have the Dragon Gates.
The idea comes from a piece of art from Dragon Magazine, I have no idea what article it pertains too - I just came across it when searching Google images.
I tweaked the Stargate concept a bit, that way I have a way for the PC's to travel quickly to different locations (not just other planets, but geographical locations and even dimensions) within the game milieu (I knwo of another DM who would hate this, remember he had a Horse plague in a game once, JUST to control his players movements). Make them a bit of mystery - thats important, only a few get to use them - so it doesn't mess up the game world!
The Dragon Gates
A Dragon Gate is a device that allows practical, rapid travel between two remote locations.
They appear as large rings composed of an indestructible grey/bronze material with nine "chevrons" spaced around their circumference. The inner ring, which rotates within the outer, contains thirty-eight unique symbols representing ‘codes’ which when combined in the correct way and number allow almost instantaneous travel between locations. One symbol always represents the Dragon Gate being used, and usually matches either the location (minor Dragon Gate) or planet/dimension (major Dragon Gate) where the Dragon Gate resides. Major Dragon Gates can also function as minor Dragon Gates if you know how to use them. The reverse is not true, you can never dial anything but a geographical location from a minor Dragon Gate.
Pairs of Dragon Gates function by generating a stable 'gate' between them, allowing one-way travel through. The symbols on the inner ring of the Dragon Gate correspond to either geographic latitudes and longitudes (minor Dragon Gate) or constellations/dimensions (major Dragon Gate) and serve to map out coordinates for various destinations.
A typical Dragon Gate measures 22 ft (though some are much bigger) in diameter, weighs around 64,000 lb and its core made of the heavy magical mineral Oricalcum*. The Dragon Gates were created millions of years ago by an ancient race of Dragon Mages and Priests - their modern history began when a young Wizard discovered their purpose some 50 years ago. Dragon Gates are still not in common usage, the language the symbols are written in is ancient and long forgotten. Only a few individuals know how to use them successfully.
When dialling a Dragon Gate either an ata-keno (a large amulet device, usually worn on a chain around the neck – much sought after as it can access any Dragon Gate) or a Dragon Gate Device (or DgD) must be used. A circular table or platform with matching symbols for the gate, each must be pressed in turn – when the address is complete the central ‘jewel’ is pressed activating the Dragon Gate.
There are definite no-no’s when attempting gate travel. You must ensure your gate address is correct (especially with major gates) or you could end up anywhere in the multiverse. Also, make sure you keep a record of the Dragon Gate you left from, without that address you will not be able to get home.
Do not attempt to pass active (as in worn) rings of teleportation or dimension door through – what comes through doesn’t live long, and isn’t pretty to look at.
*Oricalcum is a glossy, reddish-gold metal, of great magical potency. It does not oxidize, retaining its gloss indefinitely without polishing. It is resistant to all forms of corrosion. However - a peculiarity of the ore is that oricalcum absorbs blood if it is not soon cleaned off. The more blood a piece of oricalcum has absorbed, the darker red its hue grows. Some ancient oricalcum blades are glossy black. When cold, oricalcum has ten times the strength of steel, when heated - it is worked as easily as bronze. Oricalcum is found in some copper lodes. 1 lb of oricalcum sells for 2000 gp or more.