From Omerta Wiki
USMS is the User Suggestion Management System.
To add a suggestion you need to be donator+
Every user can vote every day for or against a suggestion in the top 20, after that you can also vote for a suggestion which isn't in the top 20 yet. This way the most popular suggestions will reach the top of the list.
Next to this, there is also a specific forum for the usms, where users can discuss about the ideas.