This seems like a really good idea, and one that could be helpful to people!  It would be interesting to explore different mappings between real objects and their tokens -- for example, what is the right balance between abstract and concrete representations of things people want to tag?  and how many different tokens would be needed to create a working system?  Additionally, the system for tagging less frequently needed objects (e.g. things needed on some specific day in the future) could use some further development -- having to go to a web interface might work for some people, but it probably wouldn't work for people who don't already use an electronic calendaring system.  Is there an interface that could be used at the door for creating these short-term associations? 

Finally, having people wear RFID tags is likely a barrier for adoption.  What about something simpler like face recognition, or even a weight sensor in the door mat?