Visualead is a great QR generator that combines an image with QR codes. I really encourage classrooms to use QR codes for certain lessons. I really like the idea of accessing information quickly especially within the classroom. The app that I use on my smartphone and iPad is Scan. This seems to be one of the best, free QR readers available. I think for classroom use the FREE version of Visualead works just fine.
An overview video about Visualead is embedded below.