I run 5 accounts in DungeonBuddy overnight and generally make 5k per character (from coin drop/selling green/gold bonus at the end, etc) so 25k gold for about 5 hours of work. They are all decently geared though so of course results depend on such things. The tank is a Blood DK with about 550 ilvl so he doesn't even need a healer in which case I just queue my ret paladin as Healer under Dungeonbuddy settings, so essentially have 4 dps (5 really, considering Blood DK do good damage anyway). Of course this gold amount differs every night but that is about average.
Two of the characters are also Tailors so I rack up quite a bit of Windwool cloth which I also sell on the AH. If I had an Enchanter, I could possibly make more DE'ing the greens, or maybe its best just vendoring them for gold. On top of all that, I have the bot spend the justice points on Hypnotic Dust from the vendor in Orgrimmar which sells for about 300g/stack on my server.
An average run takes about 10 minutes max, so far it has been a great way to make gold. I'm wondering if I were to get another account for a total of 6, and have 2 groups just run Random Scenarios if it would be even more gold. Haven't really looked into it though as I'm pretty satisfied with how it's going so far.