Here is a list of a few:
(url="http://"http://saberstudios.evula.net")Saber Studios(/url) (currently down)
Shade's Shipyard
(url="http://"http://www.connect.ab.ca/~bsommerf/")Adam's Shipyard (download links broken)
(url="http://"http://www.evula.com/shipyard/eeun.html")Eeun's Shipyard(/url)
(url="http://"http://www.evula.com/shipyard/")EVula's Shipyard(/url)
(url="http://"http://www.modenstudios.com/shipyard/")Meowx Design(/url)
(url="http://"http://www.geocities.com/TimesSquare/Battlefield/8064/Caernarvon.html")Caernarvon Station(/url) (download links broken)
As I recall, no shipyards currently have Nova-quality graphics (16bit, 200x200 pictures, etc.) It will be a little bit before we start seeing a surge of new graphics for Nova.
If you decide to move your plug down to EVO or EVC,and want the ships on Adam's Shipyard, I may have them downloaded, or someone else has them. Ask around. Also, (url="http://"http://homepage.mac.com/captainz")my own site(/url) has a few things up to offer, with more to come (I've been busy with my new TC plug for EVO... screenshots coming soon). Depending on what you need, I may be able to make a ship or two for you. (See my site for some examples). Good luck.