web site: based on a blueprint/wireframe view of your building. enter in as many attributes about yourself as you want. do queries on your building for attributes you're looking for.
e-pet: sure its an old idea but i think it could be huge. reinvent the tamagochi. a pet that lives in your cell phone. can migrate to your PC at will. the /. article about the "virtual girlfriend" reminded me of this idea.
if i thought i had a real chance at either one id postpone my masters degree and try the dotcom thing (again) for a while.