Large companies these days almost certainly maintain an intranet - specifically a web site targeted at their own employees. Most commonly these let your staff access many internal systems through a single portal.
Intranets can hold important HR details, terms and conditions documents, project reports, customer details or call logging systems. These can ALL be integrated into a web site letting your employees access the information securely from anywhere:
You don't need to be a large company to benefit from access to information.
Sometimes you have customer-specific information than you want to allow access to securely, such as customer account status, order history, pending project details. We can develop web sites specifically for your customers allowing them to log in and view targeted information.
Do you need to provide a web site to your customers? The best way to keep your data up to date is to make it available to everyone who needs it. Your customers could view and maintain their own contacts list on your extranet for example.
There's no reason to treat these scenarios as separate projects. We have experience of developing large integrated intranet/extranet services for 600+ employees and 1000+ customers. If you need to discuss your needs and find out what's possible, don't hesitate to contact us.