Some more for you all
Galaxy Rip: Doomsday ruin it for everybody scenario =P
It features a Trans-Dimensional Black Hole (whatever that means!), travelling at 99% the speed of light, with a mass of 100 milky ways.
It has time to travel a few million light years away before the galaxy really starts to notice the effects, lol!
Binary Neutron Star System: Took some tweaking, but finally i got a stable one! Both stars have masses, densities and rotation periods of neutron stars, try adding rings to either of those stars, the mad rotation period (and the fact that there are two of them) quickly tangles them up!
The screenshot is taken with the trails setting at about 900 to demonstrate it.