I loved popfly a lot although I haven't built many things using it, only tried some stuff and also built a simple mashup that I hosted here on the blog .. However, a lot of people has used it to build very powerful solutions, and there was a whole competition in Imagine Cup for popfly mashups..
Popfly was one of the things that first caught my attention more than a year ago at the Microsoft Student Festival .. I really thought it was an amazing tool.. I hope that one day they'll revive it..
Bye Bye PopFly.. :( Follow @evronia