If you ever have to give an overview of tidal forces in the galactic halo, and your presentation is fairly poor, you can always make an effort to redeem yourself with one of these breathtaking n-body simulations. I know this from experience. John Dubinski, astrophysicist at CITA is responsible for these clips modeling the gravitational interaction of hundreds of millions of particles to show behavior not realistically calculatable by hand. And even if it was, it wouldn't look as cool. Probably the best known of these is the predicted collision of the Milky Way with Andromeda in 3 billion years or so. There is also a film of what this is going to look like from the perspective of the sun (in this speculative outcome, our star is pulled out of its orbit in the commotion and thereafter follows a winding irregular path around the new hybrid galaxy). My favorite though would have to be the dark matter evolution clip. You can't really get a more expansive subject for animation than "history of all (dark) matter over the 14 billion year course of the universe's existence." And there are more. I dare you to watch the clip of the inside of a globular cluster and not flip out and destroy civilization like those people in Nightfall.
It isn't possible to overstate how impressive these all are. No one could watch them without being filled with a sense of the splendor and majesty of
nature n-body simulations.
[Crass alternate title: "If I said you had a nice n-body would you hold it against me?"]