Well, 日 is sun, and 本 is origin, at least in the context of 日本. It's to my understanding that the Chinese, knowing that the sun rises in the east, and Japan lies to the east of China, put two and two together and got 日本 - the land of the rising sun. Edit:
Looks like I was too slow on this one!
One etymology that I recently learned myself is さようなら - despite learning Japanese for years, I never looked into that word. I knew the word 左様 (さよう) from watching Kurosawa movies, it basically means "that's so", or perhaps "indeed". なら can be translated as "if", so 左様 + なら is sort of like saying "on that note...", an indirect way of saying goodbye. Not that easy to explain in English, but I tried
