LOL Tony, I just have one SW tank at the moment but will be setting up a second relatively soon. I started with a nano and upgraded several times.
I would not suggest a sixline wrasse (or any type of wrasse) for a 15 gallon. They are active swimmers and need more room IMO. A clown goby would work just fine though.
Seahorses require a lot of care (like target feeding) and tend to do better in species tanks from what I understand. I'd like to keep them as well, but honestly they sound like too much work for me. They aren't a beginner fish, but if you decide to keep them I'd suggest doing a ton of research first.
Some fish that come to mind for a 15 gallon include clownfish (smaller species), smaller gobies, royal gramma, firefish. Take a look at this list of "Nano Fish" and see if any of these appeal to you.
http://www.liveaquaria.com/product/a....cfm?c=15+2124
Remember that you can't stock a SW tank nearly as heavily as you can a
FW tank of the same size, so you're going to be pretty limited on your stock list. But, that doesn't mean that you can't have a lot of fun with a nano! Plus, there are some really interesting inverts, like shrimp, that you can add to your tank that don't contribute much to the bio load.