The first thing my landlord said to me before I moved in was "No holes in the walls"
I was trying to think of a fun, creative way to display a bunch of pictures while minimizing holes in the walls so I went to DI and found a big frame for $5. I then went to Walmart and bought some spray paint, twine, and clothes pins. I went home and got to work and $11 later had a fun new wall project.
Then I realized that it just wasn't big enough for how many pictures I wanted to display. So I bagged the idea of the frame and just went with the twine and clothes pins. Needless to say there are a bunch of little thumb tack holes in my walls now, but It was worth it.
If you do want to minimize holes in the wall, another fun idea is hanging a piece of twine and pinning pictures on it. I decided to display pictures I've taken from places I've traveled with this method and really like the (somewhat) clean look it gives as opposed to my picture wall.