1. IDX with easy search, map display
2. Ability to add pages, delete pages, edit
3. Comprehensive Admin. Area: leads capture, tracking and management, contact management, file uploads, transaction management, etc.
4. Maybe a blog to help with search engines.
Main reason why people are coming to our websites is to search for listings, anything else is secondary. Easy and simple access to listings is the main ingredient for a real estate website.