If you're interested in social software, then the idea of "mashing" or "mash-up" is an important concept to understand. The Economist provides an introduction and discussion of the future direction in social software mashing. They explain mashing as:
"The term mash-up is borrowed from the world of music, where it refers to the unauthorised combination of the vocal from one song with the musical backing of another, usually from a completely different genre. Web mash-ups do the same sort of thing, combining websites to produce useful hybrid sites and illustrating the internet's underlying philosophy: that open standards allow and promote unexpected forms of innovation."
I've mentioned a number of examples of social software mash-ups on this blog, including:
Tags: mash-up, social software