Great question! I'm curious to see what others write here.
I have and have had some rarities. I have fish that I have collected myself which is quite rare. I also have many Atlantic fish, including a harem of Bluehead wrasse Thalassoma bifasciatum and a crested goby Lophogobius cyprinoides. I have surge towers and dump buckets to cause waves in my tank. I have a Salt Lake City tank raised clownfish (Anemonefish that is) that is now 3 years old. And best of all... I have some corals that I personally collected.
Adam