Of course I start every blog entry off with the definition from wikipedia. Wikipedia says a mashup is web application that combines data from more than one source into a single integrated tool. The definition matches the name. A mashup is an application that can mix and match qualities from each application you like. If you like certain qualities about on application but dislike the rest or would rather have another part to replace it it is possible. It creates a new application. Each application waqs designed for something different but ends up creating something totally different.
An application that does this is Yahoo pipes but there are a lot more such as teqlos, dapper, proto and openkaphow. An application that you can create with them is mixing yahoo local together and an apartment finder sight such as Craigslist. The yahoo local allows you to know where it is located and directions while the apartment listings will sort through apartments by size, price, and distance. This is where yahoo local would come in you could find the apartment and it would also show the distance between your address and your destination. Another example would be Flickr(a image an web hosting site) and the New York times. a pipe which takes The New York Times RSS feed and adds a photo from Flickr based on the keywords of each item. A piece pf Flickr is taken with the New York times an it is mashed up to create something new.
Also for example if you wanted to know where crimes were mostly commited in your neighborhood you would access the API for crimes and then use yahoo maps if it showed a map of where crimes were created in your zip code. Or access a single persons API and then yahoo maps. You could create a mashup by putting them both together and have a map of singles in your area. I love purses and my favorite brand Juicy couture. I maybe would want an API to malls that sell the purses and use yahoo maps to see all the malls in dallas I could have a new API that shows me all the purses in different colors and which specific mall to go to insted of calling around.
These applications affects me as an interactive designer because some clients will want things that are no neccersarily created yet. If a client tells me they like a part of an application a lot but really dislikes another years ago they would have had to take the good with the bad. But now it is possible to elimiinate what we dont like and create something that we do. The combinations are endless. No one has to settle for something they don’t want.