While I'm a strong proponent for P2P for some things I don't think that is the main issue here. So, I'd like to examine how a shared database gets filled with lots of what people want. Another example is the old legal databases where armies of typists were paid to retype printed material into computers. Newsgroups and SlashDot are examples of volunteer databases, where interested individuals provide the data because they feel passionate enough about doing so. Many databases on the web today are mechanically created by getting access to somebody else's data, sometimes for a fee.
Examples are the street map and airline flight status databases.
Some of those databases are by-products of automated processes. A more interesting one to me is the CDDB database . The CDDB database has information that allows your computer to identify a particular music CD in the CD drive and list its album title and track titles . Their service is used by RealJukebox, MusicMatch, WinAmp, and others. The title information is not stored on most CDs .