There are many solutions available for creating a shared workspace. The solution that's right for you will depend on the functionality you need.
To connect an entire company, a robust solution like Microsoft SharePoint might be best. For a small team working together, a simple site built on open source wikis could be the answer. Learn more about these solutions:
Other Considerations
Depending on how you use your workspace and how many people have access to it, you may need to develop policies for acceptable use and appoint a moderator to enforce them.
Also, consider your budget and staff resources. If you have an in-house IT staff, will they have the time to build and manage the service or is it more cost-effective to outsource it to a third-party vendor? You have many options available to you, so determine how much you can spend before choosing a solution.