Sarah C. from the 11:20 section has shared this excellent collage creator for both PC and MAC users: Shape Collage. From the site:
About Shape Collage
A free automatic photo collage maker that lets you create picture collages in a variety of shapes in less than a minute with just a few mouse clicks. Shape Collage creates collages using an intelligent machine learning algorithm that automatically places the photos in the collage and can arrange the photos to form different shapes.
Thanks, Sarah!