Hey there dear reader i hope this guide will help you ease your travels around the world of warcraft. This guide is most useful on chars that still don't have all the portals for the zones in cata and for chars that are still leveling. This guide relays mostly on portals that are obtained by quest chains or are a part of a quest chain.
So lets begin:
Well this is all that you need to do its not so much tops 1 hour of running around doing very original and fun quest's.
As for what this can be used to i think it simple:
You can go from lest say Blasted lands to Ungoro in 5 min using the dark portal -> Shat -> Dalaran -> Use CoT portal or Basin waygate (using the portal that "Where in the world is Nessigvery" opens"
Porting to Tanaris from Shat using Dala Cot portal.
Nice thing to point is that also Sholaz Basin waygate works back and forth.
I will leave the rest to you.
P.S. Nice thing is that blizz can't fix this without braking there quest chains so they can not fix it if they don't like this.
Marry X-mas all