[AnimalMuppet]

Apart from dragonwriter's point, that you're just duplicating the signaling that money currently does: You want to let some central authority watch every purchase I ever make, just so that they can try to plan the economy better? Um, hello? Privacy concerns, anyone?

[yorwba]

If you don't need your ${purchase you'd like to keep private} to be optimally produced, you could register demand for a facility that allows you to select from an assortment of goods effectively anonymously, i.e. a shop. The demand would then be tracked on the aggregate level. Of course this is assuming that the selection includes what you want, otherwise you will have to be more open about your desires to have them satisfied.

[utexaspunk]

That's a separate issue, but I imagine there's probably a way to collect the demand while keeping the individual anonymous. Besides, in the world of capitalism we have the same concern- Amazon, Google, my bank, and Verizon could all probably tell me things about myself and my habits that even I don't know.