the shells one would be a good one also maby one for macro algae/algae (it would be had to make algae look good but im sure d2 could do it lol) or breaking up some of the corals like zoa's/pally soft/lps sps/non-photosythentic. also fish month might as well be renamed mandrrin month lol (jk). there are good themes now but might be nice to mix it up a little for the new year :)
or maby open up two themes per month the saltwater and say non-saltwater pets or nature things like that but still only put the saltwater pic on the main page because this is a saltwater fourm first. would make more work but would open up for some coll pic's