Yahoo Pipes enables users to aggregate existing data to create and share a data feed using a visual drag and drop interface. Its a great idea and when you’ve used it you may wonder why nobody has done it before.In fact they have, but just not on the web and in such a visual and open way. The idea of Pipes comes from Unix pipes (|) which let you take the output of one small program and use it as the input to another. There have also been a number of enterprise products, such as BEA Liquid Data, which are much more heavy weight, but embody the same principles.
However, now Yahoo, who are not renowned for developing the own products (you would have expected this from Google) has brought out Pipes, providing everyone the opportunity to make pipelines to merge, sort and mashup data already on the web. Keep an eye out for useful pipelines there are already ones in place replace the results with Flickr images that match the content and keep track of eBay items. Take a look at the most frequently run pipes page.