This is really just an obvious method, but not many people think about it.
Items required:
*Level 90 Healer or Tank
*Decent iLvl
*Steps:
1. Wait for LFR to need a healer or tank as the Call to Arms
2. Queue as whichever fits your role.
3. Complete the dungeon, and you will receive a Satchel of Cosmic Mysteries
4. This is tradeable cross-realm, and can contain anything from companions, mounts, flasks, elixirs, battle pet stones, etc. but ALWAYS contains gold.
The gold amount is usually around 90-100g, but the chance of a companion is 0.2-0.6%, which isn't too bad. These companions sell for anywhere from 300 to 3,000g on the auction house.
The chance of getting gems worth 50-100g is 4-6%, and happens to me almost always.
This isn't a huge amount of gold transfer, but it is extremely useful for those wishing to start anew on a different realm.