This semester I am the TA for the numerical techniques class offered by my department (as in I am the only TA). For the class the students have projects where they demonstrate some numerical technique by solving a somewhat more advanced problem. One of my students had a project where he was trying to show gravitational lensing. He loaded images taken by Hubble into Matlab and then calculated how the image would be warped by a black hole between us and the target. With a little help from me, and a lot of work on his part, he managed to make a short video of what the Andromeda Galaxy would look like if a black hole passed between us and the galaxy.
The strength of the lensing is greatly distorted (I think he assumed a black hole of > 10^12 M_sun) in order to emphasize the effect. Still it looks pretty cool.
Below are some real pictures of gravitational lensing for comparison.