I am new here - so there may be something affecting my suggestion here that I am not aware of yet. I am noticing that there are a lot of people offering loans, and a lot of people wanting loans. However most of the people offering loans specify it is for "trusted" server members. How about setting up a credit rating system to help quiet server members who aren't well known (and newer members) build up a credit rating to help with loans? This would, I believe, require an "official" loan system, offering small loans to builders - perhaps even setting up a system that allows collateral to be placed against a loan. Time on the server would help upgrade the credit rating system. Donations and buying things from the server shop could help with credit rating. There is a lot that can be done with this, and it can be a relatively simple thing as well as a pretty complex thing depending on how far you want to go with it.
We already have a credit score system of our own - The ban appeals and complaints section plus the users' ranks/donations. Implementing a full-on "credit score system" would be lots of work, not needed and above all, unfeasible. When making loans and doing other financial agreements with players, be smart - Look at their ban/complaint history and such. When taking the proper precautions, you should be safe when doing financial transactions with players.
This isn't a bad idea, in my opinion. I just think it'd be hard to set up and balance correctly, and isn't exactly something that the developers time should be spent on, at the moment. But doing what United said and sometimes just simply asking in chat if a user is trustworthy helps. If you are a new user looking for a loan, you could start off small and then use the people you loan from as a reference.
I think this would be a fantastic idea. Every fulfilled contract could produce positive credit and every time a mod had to nanny it to completion, negative but every time someone did stick around and figure it out it would repair it somewhat. It would prevent so many unscrupulous loans and it would add a new dimension of gameplay for all users because a good credit score is the finest financial achievement even irl imo. And now would be a fantastic time to implement it as a part of the "back bone" bank system to prevent untold amounts of loan scamming that will happen when the new servers come about and everything is fractured somewhat communication-wise. Maybe it wouldn't be the simplest thing to implement but it would add a lot and honestly when I showed up to the server I too was completely baffled about this "hardcore" economy not having anything like a credit score and like being back in the stone age as far as that economical facet goes.