If you are looking for a Hosted Intranet solution then SharePoint is probably your best bet.

Microsoft SharePoint is a web-based document management technology that comprises of project collaboration, document workspace, meeting sub-site and discussion board features. All of the aforementioned features allow for organisations to collaborate and share information actively and increase productivity. Microsoft Office SharePoint Server, otherwise known as MOSS is a versatile solution that allows it's users to maximise the efficiency of a business processes and streamline productivity, as well business continuity and additional security features.