Yesterday I went to a talk on "mashups". Mashing, in techy speak, is when content from more than one source is combined into an integral experience, so for instance feeding in flickr photos or an rss feed into blogger or another website. Fd's flicker toys, which I'm always blogging about, also "mash" as they use the Flickr API to feed in photos and search flickr to create snazzy photo art or perform other functions. Flickr seems to be one of the "in" things to mash at the moment and funky little programs are cropping up all over the place. For instance tagnautica is a browser that allows users to explore the huge flickr image collection by using tags as keywords to classify images, meanwhile the retrievr sketching search engine is an impressive gizmo that allows users to search and explore Flickr images by drawing rough sketches.
Mashing creates many possibilites - we can extract certain types of data from a database such as < date > or < location > and create timelines of events or place markers onto a map (see google maps). Mashups, as of today, are mostly a programmer's affair although there are some tools such as MapBuilder that can help you create basic maps without coding. I'm going to give it a shot though, it's very "in" in the world of Web 2.0 (if you believe in that kind of thing Mr Berners Lee).
The Programmable Web