We use Confluence for this purpose. Some investment is required in building a template to capture the requirements from different stakeholder groups' points of view but this can be evolved over time.
Anyone can access (with appropriate read/edit rights) at any time so good for fostering collaboration.
We encourage stakeholders to update the information and ...
Activiti is designed exactly for this.
It is a workflows engine, and is open source.
Unlike SharePoint, it is standards-compliant and well-documented.
First, create the workflow definition:
Then, use the worflow, either in your custom UI or with the built-in UI:
Should you need to check the database, it is not far away:
You can actually choose the ...