This is rather simple, and might have been posted allready. But, any public quest gives an XP bonus every time you get to a new stage. So if you find a nice spot where you dont get attacked in a public quest that gets done a lot (welcome to troll country is a great example) you'll get about half as much XP as if you were actively doing the quest. This can be done with any public quest, and is probably faster and safer then AFKing in scenarioes. And, you get to roll on the loot. :P