It can be done, but probably not easily. I believe you would need a fully trusted form and code to harvest contacts from Outlook.
You could export contacts to excel or a database and then access them pretty easily using standard methods but of course you would need to update your list from Outlook frequently.
You also maybe interested in our Active Directory Web Service. If you need name, email, manager, etc for users in your domain then that can be done pretty simply using the web service.
Otherwise you need code or to keep your contact list in XML, SharePoint, a Database table, etc.
Qdabra Database Accelerator Suite Version 2.1 - Developer