i may have posted the exact same thing earier but... another web2.0 idea is identity management. once openid (or similar?) catches on, the one thing ive learned is: As soon as you have single signon, it disappears. What matters then is where  your identity is maintained and what tools you have to maintain it. openid opens the door to this.

i want a local server (or a web service for those not so inclined) that knows a whole lot about me. name, address, shirt size, likes, dislikes, photos, sounds, common physical locations, etc. that is highly secure. i keep that info in just one place and all those websites have to go to my identity provider for details. i have fine-grained control over who gets what. If im at a tshirt website, i want to say i want 3 shirts in my size. it asks my identity server for those measurements. Or maybe if im at a firstlife(real world) clothes store, i stick a USB drive into a tabletop that authorizes access to  my measurements on the identity server.