I've disected a ...
fetal pig: the point of the dissection was to understand about our (human) anotamy better. pig's resemble humans the most guts wise...
sheep heart: the point of this one was to get a visual understanding of the 4 chambered heart, 2 ventrical 2 atrium structure
cow eye: the point of this one was seeing the various layers of the eyeball, the optic nerve, vitreous humor, etc
dissections are fun!
edit:
I just remember I dissected a pregnant fish before too. It was just a small one, can't remember for the life of me what species though....