In regards to Nost, this was taken from mmowned. It doesn't explain the exploits, but gives enough hint that the devs here may be able to squash them now:
Hi,
I'm willing to trade two exploits that I currently sit on. No, the dupe is not up for trade.
No I'm not selling gold on nostalrius.
1. Quest item that prevents you from entering combat: This can be used to farm chests everywhere, mobs won't attack you when you have/use/wear this quest item.
* I am also trading a model edit check bypass + model edits for farming chest is also up for grabs. This allows you to walk underground and farm chests in Winterspring, EPL and WPL.
2. Bugged quest that can be done over again, this quest gives you a item(s) that vendors for 3g+ and can be farmed quite a lot.
When trading with me you will be vetted to make sure someone from the Nos staff isn't trying to get a grip of these exploits. Only taking other exploits as payment.
EDIT:
To clarify, I haven't used these exploits myself on Nost. This seem to have gotten a lot of people all riled up. These exploits has been confirmed working by 'friends'. I am not selling these exploits for ingame gold/items/real life cash as I do not intend to profit from the exploits. I only accept other exploits in return.
And I'm sure, if Nostalrius' cheat/exploit detection is as good as they claim, they will surely be able to detect / find out if I or others have used any exploits