If you have a team of warlocks, or really at least two locks on different accounts, you can play the summoning game.

The leveling guides, like the Kopp/Joana guides, get you all the flight paths as part of the leveling process. Chances are one of the free leveling guides would do the same. Scanning something like this, will get you a semi-efficient route to run. Or google might find a better path.

I remember getting multiple levels, from the Halloween candy buckets during RAF. My priests, death knights and hunters aren't quite 75th (and need to be, for 525 alchemy), so I did candies with the priests. Unfortunately, almost no old world flight paths made this slow, and after getting only 15% experience for an entire continent I quit; the experience per time played, is much slower then just questing.
I won't bother with old world flight paths, until my toons can fly.