Here are some other space art forums I've found... feel free to add more if you know of any!
Solar Voyager - http://www.solarvoyager.com/forum/default.asp
(reasonably active, focussing more on planetary and star art than spaceships)
Scifi Meshes - http://www.scifi-meshes.com/forums/
(mostly spaceships from big SF shows).
Nova Celestia - http://www.novacelestia.com/index.html
(lots of pretty stars and planets pics here)
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