My personal favorite is vending.

I also collect trash and stuff in towns when I'm bored and have nothing better to do, and zOMG is a pretty good source of income if you have the time for it.

What are your guys favorite methods of making money?

Actually, lets write a money-making guide for Gaia! Everyone can write a section! Do you collect trash a lot? Make a trash-collecting money guide! Play zOMG a lot? Make a zOMG one! In the end I can compile them all into one post and give all of the original authors credit. You guys wanna?