Flickr Mashups and Tools

I had a lot of fun playing with all the different third party tools available for Flickr. I still don't think I quite understand the concept behind mashups, but maybe it's just the incredibly technological terminology used to describe it (I keep thinking about mashed potatoes). Flickr Color Pickr intrigued me the most. I'm still not sure why someone would need to find pictures in a particular color (possibly for display purposes?), but I had fun playing around with this tool anyway. I think the idea of creating a library trading card sounds incredibly outrageous (in a good way) too.