CollageIt - CollageIt is an easy-to-use and automatic collage maker, which makes photo collage automatically.
Fotor - Fotor is an all in one visual platform. It includes photo editor, collage maker, and graphic designer. You are free to make a visual look more beautiful.
PhotoSpills - Easy to use PC collage software with unlimited design possibilities.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
Collagerator - Create amazing photo collages in few mouse clicks. Ready for download for Mac OS X and Windows.
GIMP - GIMP is a multiplatform photo manipulation tool.