I'm starting a business and would like to use the internet to do lead and expense tracking along with communicating (email; fax, etc.). The goal is to have information available online instead of being stored on a single computer this way I can access it wherever I'm at.
Is there one online platform that has what I'm looking for and works fairly well (hopefully low in cost)?

Look at Google docs: http://docs.google.com/

Try OfficeZilla. It is free to use and there is no limited on how much space you can use. You can even create usernames and passwords for your clients and/or employees.

Free Web Based Intranet / Extranet

The only problem with keeping your database on another companies server is if they go out of business, so do you.

Have you tried Gotomypc.com? It allows you to access your computer from anywhere that has internet access.