I found one mashup that plots the hometowns of American Idol contestants using Google Maps and Yahoo Geocoding. There's also Podbop, which is an application that combines band event data from Eventful with mp3 tracks. You can type in a city, get mp3s, and if you like the music you hear, find out when and where that band will be appearing in that city. ParkingCarma combines event data from Upcoming.org and local parking facilities. Useful for finding parking for the events you plan to attend. Visit www.programmableweb.com/mashup/ for an "index" of mashups.
What I find amazing is that there are hundreds of mashups and third-party sites out there and people are creating more each and every day. So many possibilities.
I made a trading card. Neat. This one is about my golden retrievers, and I used a photo of my own. I can see kids using this as a product--a way to present information--and also as a way to collect information as they find it. It can be used as a writing tool to help students prewrite characterization for a character or as a reading tool in collecting the text clues to characters' traits.