I agree Justin Tan's tank is breathtaking and beautiful. I am also particularly impressed by these two and would love to build the skillset to copy them:

(I would have preferred another species instead of the water gimmick, but just gorgeous and looks easy to maintain long term)
http://www.aac.acuavida.com/gallery/...P0088.jpg.html
(maybe the best use of a cube I have seen. Just great.)
http://www.aac.acuavida.com/gallery/...P0058.jpg.html

Inspiring collection and super interesting tanks. The kind I get close to the monitor for to check out little bits of the tanks!