I've recently collected about 300g without doing anything but sitting in Org for a few hours mailing items.
How you ask? I think I've come up with the ultimate mail scam.
To start, go to General goods vendor and buy about 200-300 wrapping pappers (45 copper per paper). Also fill your packs (all 16 slotters empty) with blacksmiths hammers (16 copper). Wrap all the hammers. Sit at mailbox clicking on 60's walking by and type in their name into the mailto (or just open the who list and search for 60s on the server), put 1Gold COD (or more!) and put the present. send. move on. don't even put a message, you could if you really wanted to but I find this a waste of time. Just keep doing it, find guy, click, type name in mailto, put prezzie in 1gold COD and send.
You'd be surprised how many people will pay 1g to see what's in the box.
WARNING: Use this trick at your own risk, people have made a LOT of gold doing this but also take the chance of getting banned, be careful.
Also helps to have a weird character in your name so they can't whisper you. My name was ÁrrakBBlizzmade me change it because of this. I know this is a nice little trick, but if your serious of making tons of gold quicker and in a more legit way then you may want to check out a guide a lot of people have been talking about lately, the Valkor's Gold Making Guide, there is a small fee for it, but it is worth it in my opinion.