This was the first thing I had never heard of before. The term "mashups" brings to mind what I eat the days after Thanksgiving!
On a more serious note, I can't believe how many of these sites are out there. I love how Flickr even encourages use of their site! Of all the mashup sites I browsed, I must admit that my favorite was also the trading card. I can see so many uses for this as a librarian! Students (or teachers) could create cards for book characters, genres, themselves as a reader, a topic they researched, etc. The possibilities are endless!
On the other hand, there are a few mashups that are fun at first but I got bored with very quickly and just didn't see the point. One of these is a game called guess the title. I was intrigued at first, but after 5 minutes of playing the game I became very frustrated. I couldn't guess any of them! Noone named their pictures anything I could tell from the picture itself! Although, I guess you could argue that it did pass the time.
Whether the mashups were fun, useful, or unproductive, I do enjoy that Big Huge Labs lets you upload from multiple sources such as Flickr, Facebook, and a file saved on your computer. This way you don't have to take that extra step of publishing pictures to a site before using the program. This way, librarians and teachers can take pictures of students, projects, or books and create a product immediately!