Creating an effective game economy is hard no matter what sort of game is being created. The relationship between the economy and game flow cannot be understated.
Amit Mahajan from Zynga provides a good overview of economy and social interaction.
The Dubit Platform looks promising as a tool for creating the basis of your economy. The image at the top of this post is from their good post on designing a social game economy.
I haven’t used their tool yet, so I can’t comment on what it’s like to use it. You can access it here.
Cafe World is a Facebook game that has an economy that you can see in spreadsheet form. An obviously out of date spreadsheet of their game is available on Google Docs.
If you know of any other tools for designing an in-game economy please let me know!