Imagine a site where anyone can enter data, edit previously entered data, and define new types of tables. But why not take it further, Wikipedia style? Ouseful has a few posts on collecting data that’s already out there, and mashing it up with pipes and Google Docs.
So data is already public. But not accessible. Want to make a semantic web? Make the data easier to access. Start by collecting it.
Collecting it is a huge job. Obviously get the entire Internet to help you by allowing anyone to edit the collected data. And there will be audit trails (histories of changes), Wikipedia style.
View my ongoing work at http://data-everywhere.appspot.com