Wee Birdy has a very cute and very simple (READ: easy) idea with this giant wall confetti!
Now, this picture from Oh Joy! didn't seem to have any instructions with it, but I love this idea! If you take streamers or ribbons or whatever you would like for the background and sandwich the tops of the strands between two pieces of tape, you would easily be able to hang it on a wall or between two posts.
Oh Happy Day had a cute idea for a circle photo booth backdrop, which is absolutely adorable. However, to make it a little less complicated, you could swap out the sewing machine and just tape the insides of the circles to the thread.
For holiday times, I love string lights as a backdrop in pictures. Instructables has a neat How To to make the lights diffused and less glaring by covering the little bulbs with ping pong balls!
I hope you liked some of these! Please let me know what you think in the comments below and share your ideas!