I actually saved a magazine of some home decorating mag my mom always got in the mail cuz it was a sea theme
One of the things they did was took a large mirror and glued sand and shells and starfish to it (it looks really awesome)
Also, they had a fishing net... er lobster net... as a canopy
If you havn't purchased your curtains n stuff... might i suggest a solid color... like seafoam green or something... that way you can decorate with items, and not have prints. Because in 5 years you might not like the curtains that have a print to them.
I like to think im pretty good with decorating, so if you want any other suggestions.. or if you want me to dig up that mag. for ya.. PM me =o)