Fastest place to farm gold
From what I have read on various websites, everyone generally agrees with Thebluefish' comment.
At level 50, every 75k exp. gets you an Elder Gem. Once you've reached the Elder Gem cap for the day, all experience points you get will be converted into silver.
From what I've read it seems you can farm 60 gold to 80 gold per hour, given that you've found a good spot to farm.
Note: This information was gathered from players who reached level 50, meaning that it's speculation, but backed up pretty well.