Yeah I think a lot of people keep nano's but don't talk about them too much .... especially based on that *other* board. J21Kickster has a rocking nano as well ....
I used to have Brooklyn Johnnies saved but I can't find it anymore - if you can please bump it up DVSKIN.
Personally I think a seahorse tank is a lot different then nano reef.
Personal belief - in a nano reef you want everything to stay proportional - so you would want to keep small corals or coral frags. I just added a bunch of frags and they look awesome. In a ten gallon I think you could keep something a little bigger than what I have in my 5 gallon, but I think full sized corals or large versions look out of place in a small tank - that is just my opinion. So if you can get some small frags and have a larger tank to move them to in the future you can grow frags for a larger tank and move them later.
In a seahorse tank I would think you would want branching corals/rocks and maybe some small sponges and macro algea that they can latch on to and hold. You would also not want as much flow or light which would limit you to some 'shrooms, some polyps, xenia maybes and some other low light corals. The issue is it is hard to find a low light coral that is also not a low flow that stays small and would fit into a seahorse tank.
I have seen some awesome nano's that are dedicated to seahorses but not sure if I recall a straight 10 gallon one ....
MODS: delete if you need to - but go out and check
www.nano-reef.com