I think what you are suggesting is a good idea. Maybe if you are wanting to know both what is and what isn't you should have a separate thread?
I would be interested in people listing what they have kept successfully with their seahorses.
My list of suitable tankmates:
Clown gobies
Pajama cardinals
Banggai cardinals
Engineer gobies (these guys have been perfect citizens despite their size, they spend all of their time in burrows and will catch food as it floats by, sometimes they will come right out and hover to eat but ignore other fish and inverts and vice versa in my tank)
Mandarin fish
Scooter blennies
Pipefish (bearing in mind I live in Australia so I purchased captive bred SH's and banded pipes)
Peppermint shrimp
Dwarf yellow tipped and yellow striped hermits
Handreckii hermits
Trochus and turbo snails
Red handed shrimp
Possum wrasse (small and shy)
CORALS
Duncanopsamia
Scolymia
Acans
Blastomussa
Zoanthids
Morphs
Xenia
Star polyps
Soft corals such as Sarcophyton, Klyxum, Cladiella, Nepthea etc
