Dan Gillmor, who blogs at bayosphere and wrote We The Media, is writing a series of columns on citizen journalism for the BBC website in the coming weeks.

His inaugural column covers some familiar ground: blogs, wikis, podcasts and whatnot.

Here's something new:

Web mashups

In Silicon Valley, the current rage is called "web 2.0" - a reference to the web as a computing platform in its own right.

As more and more companies give third parties a way to combine their web-based data and services with other companies' data and services, clever folks are mashing things together in remarkable ways. For example, check out ChicagoCrime.org, which puts government-provided crime data on Google maps and lets people drill down into detail.

Now add to this the idea that everyday folks can start annotating maps and other kinds of information on their own. The possibilities seem endless.