In the case of national unity, it seems to have been most effectively implemented by various Chinese dynasties (in fits and starts, of course) and France under Louis XIII and Louis XIV. Famously it was seriously pursued, but luckily not especially effectively, by the Nazi regime.
The case that amuses me most is famous to English speakers, is of course cited in the Wikipedia article: the emergence of a blended "British" culture in the reign of Victoria: Tartans being the most famous, but also national anthems, brides in white, today's formal fashion (suits, military dress uniforms, and the like) and so on. What amuses me most is the ad-hoc nature (so consistent with how the british developed an empire) and especially how widely it spread: North Korean military uniforms look like 19th century upper class dress and Japanese weddings remind one of Victoria's.