While I wouldn't want to discourage hacking and alternatives, that sounds like duplication of effort to me. What do you plan to do that http://pinboard.in/ isn't doing already?
Well how about an open and federated system - all alternative suggestions so far have been single sites owned by somebody else. If we could build a system which stores our data on our own server with the ability to connect to others then it would be far more sustainable - like status.net is to Twitter.
