Fellow gamer Robert DeVoe has created some great-looking alternate deck tiles for non-Starfleet ships, and has allowed us to host these here on our site. These are available in two PDFs.
new tiles 1 (PDF, first four images)
new tiles 2 (PDF, last three images)
Nice. A lot of the textures seem a little hard to fit into a Trek aesthetic, but I could take that as a challenge….