Writing an alternative interface to Facebook

Hypothetically, suppose I wanted to produce an alternative user interface to Facebook. How complete could it be and what would be the most important features that coul开发者_如何学运维dn't be implemented?

You probably would be able to reproduce about 5% if not less.

• You would stuck right away at login form as it cannot be reproduced outside of facebook :) You can't login through API without forwarding a user to facebook web page or popup.
• You can't register a new user either.
• Search abilities are very limited. You can't make any detailed searches through Graph API. Using FQL wouldn't help much either as 90% table fields and not indexed and not available for searching.
• Most data queries are limited to latest 5,000 entries, anything older is invisible to API.
• What is public on facebook site not always visible to API without extended permissions
• Like button cannot be reproduced
• There is no API for creating new applications

and many more...