For lack of a better way to describe what I'm looking for:
Can anyone recommend a SaaS application that provides a secure client portal where a company and its clients can upload and share files, send messages, and that allows invoicing and online bill payment? Security is important as some files contain sensitive information, SSL required.
I feel like I'm sort of looking for a CRM or something, but not really; and it's almost like base camp, but not quite. Ideas?