This was posted on WowInsider, but thought i would share this here
It's a calculator for rep.
Mobs you can kill, quests you should do, instances that you should do, all that result in reputation for that faction.
Just type in your character name, and choose your realm, and there you go.
This ONLY works for EU players however, and i'm US, but someone should find this usefull ^^
http://reputation.mygamesonline.org/