Bit of a lo-fi hack, but a handful of small bulldog clips held up with veneer panel pins (a.k.a. small nails) works nicely to hold printed pictures.
I left a nice wide border on the printed images to act as a frame for the shots (printed on a basic inkjet printer), and I think it works nicely above my desk.
They will likely start to fade and curl with time, but to be honest I'll probably be bored with the shots by then, and they will be really easy to change out.
I love framing pictures, but this is a simple alternative for cases where you just want to have a nice revolving gallery of images.
Another possible way of doing this would be to use wooden trouser (US: pants) hangers (wooden ones with metal clips on a rail that you can slide along) as you would only need a single nail, however the above works well for a smaller double-stacked wall space.