Using the interwebs as they are now I perceive the following tensions.

Online identity:

* the desire of privacy dictates that we centralize as little as possible: atomize our online presence over the different sites, using a different nick every time, so that none of them is traceable to us
    
    * convenience dictates that we have use single-sign on to identify ourselves once and for all, but this introduces a single point of failure - as well as making us more traceable if not done right (using different personas under a single identity).
    

Attention economy:

* we want to keep control of our own data, keep our cards to our chests wherever possible
    * by using convenient sites like last.fm, facebook, google and yahoo applications, and handling single sign-on through external sites, we agree implicitly to donate our inputs to the site owners, who can sell it (hopefully anonymously) for commercial use.
    

One partial solution to keeping a hand on our identity and our data is to host most of it ourselves (php-OpenID, hosting own node in decentralized social network like DiSo, our own chat server, our own microblogging node, whatever else).

As the convenience <-> privacy contradiction shows, this is only open to geeks for now - you need your hosting, and some skill at installing all this.

Maybe it would be interesting to create an easy to use version of this for the other people ? Something easy to install - a package, a click-through interface, a customized slice ? what do you think ?