Photoshop can do this but it is not 'simple'. Gimp should be able to do the same.
I use Photoshop to make something like old 'contact sheets'. Make one basic background with a layer. Open files and paste them. Each can be cropped, dragged or overlapped and the combination can be processed or saved in many ways.
I use Photoshop to make something like old 'contact sheets'. Make one basic background with a layer. Open files and paste them. Each can be cropped, dragged or overlapped and the combination can be processed or saved in many ways.



It doesn't work for me on Vista, though, so it's not much use now. And as you observe, I already have access to multiple alternatives...