Collagerator is a Windows application that allows you to quickly and
easily merge photos into an appealing collage. It’s not portable, but is
completely free and there are no restrictions requiring you to purchase
a premium version in order to gain access to them. You can assemble
photos into several different collage styles, and you can use various
effects to make it more attractive. You can export the final product in
using one of several different formats, including PNG, BMP, JPEG, TIF
and more. Additionally, you have total control over the output
resolution of the collage.