In my opinion this is the mother of all multiple forum sites. It is the official online forum of TFH magazine so you can imagine the amount of information you can get here... They have everything from fresh water, aquatic plants, marine, puffer to cichlids. It is easy to navigate and to find what you are looking for. They have excellent moderators so you don't get any spam or trash in the forums. It is definitely worth to join.
http://www.reefresources.net/
Exotic Marine Fish
Dwarf Seahorse Aquarium
Reef Tank Pictures
centropyge argi, cherub fish