Mass Effect: 

In the first image below, we see a picture of a crater on mars. However, due to the light source in the leftmost picture, we see a dome rather than a crater. The light source in the left crater makes this less ambiguous and allows us to see the crater instead of a dome. I imagine this may have caused some astronomers some confusion.

In the second image, we see the silhouettes of the cast of Mystery Science Theater 3000. Pay attention to the rightmost character, Crow T. Robot. Due to his construction and the lack of depth from the silhouette it can appear that his head is facing the viewer rather than the film. Knowing this, it is possible to switch one's perception of his head by imagining where the beak is pointing. 

This effect is not limited to visual images. You can see an example by simply repeating a word to yourself. Say the word "life" to yourself repeatedly. Eventually, you can start to hear the word "fly". Knowing this, you can switch back and forth between hearing "life" or "fly" while still saying the same syllables.