Some ideas and key components of a well developed membership website should include (please add to the list), but are not limited to:
Newsletter Sign Up
Different Level Member Registration Forms with Payment Processing
Member Center or Account Management for Users
Member Networking (Forum, Blog, Messaging, File Upload, Video Sharing, Groups - something a la Drupal Commons - but with Single Sign On)
Membership Directory for Public Search (we are actually working on an integrated Google Map View to show front end users the location of the member within their profile - if anyone has done some work in this area or has some good examples, please post)
Back-end:
- Member Management (payment processing, automatic invoicing, automatic renewal reminders, member reports, automatic member upgrade to different member level, etc)