-The Pokemon anime, the first season of the English dub of which entertained me quite a lot when I was a kid. Hell, Pokemon in general, or I might as well go out on a limb and just say Nintendo. All their first-party games are awesome and the consoles rock too.
-Touhou Project. That's a no-brainer (to anyone who knows the series, anyway.)
-The language itself is pretty awesome, and even though some internet-dwellers and Mary Sue writers use it gratuitously, it's fun to trip those people up when you know more actual Japanese than they do. I've never actually done that, but I think it would be fun.
-Godzilla. Everyone knows him, even if they've never seen the original films by Toho (not to be confused with the game series.)
-Japanese food. And I don't mean rice, sushi and ramen. Once you actually try proper Japanese cuisine, I promise you'll fall in love.
Let's just say: Nihon wa sugoi desu ne? (I would actually type that in Japanese, but this website can't read it... ._.)