Cool Starship: Basically, see Cool Chair, only slightly less prevalent due to starships being more expensive.  And, in fairness, most starships are functional things.

But there are a lot of custom jobs floating around there.  But of particular note, probably, are the Celerissima-class yachts, the smallest and least practical lighthuggers ever made for meat intelligences; the God of War, as mentioned under Deus Est Machina; and Sovereign of Stars, largest of the Imperial Primes, which is basically a medium-sized palace and its grounds fitted out with life support, engines, and other spacegoing appurtenances.