For me, the ability to quickly search all my tagged stuff from all the services I use is the most compelling part. Consider just focusing on that. Have a short

For me, the ability to quickly search all my tagged stuff from all the services I use is the most compelling part. Consider just focusing on that. Have a short video that shows exactly how it works on the left. And on the right have a box that allow users to input their credentials, rss feeds, whatever you need, for all their web service and then begin searching all those services with a searchbox that auto-completes as they type. Allow them to do all that WITHOUT having to register. Store a cookie that connects that user to all the info they just inputted which is in your DB. Then tell them to register to save that info. Why require them to register first? If they like your service, and put all that time into adding their info, they will register.