When I first started learning Japanese, I got addicted to building vocabulary lists. Some topics I chose were common action verbs (I came up with about 600), sensorial adjectives (including colors), abstract adjectives, anatomy, clothing and their specific verbs, household objects, weather, geography, and animals. It's from that process I was able to usefully find out their word for brain is pronounced much like know.
It goes without saying, but 2ch is an extremely funny place. Being able to follow some of the discussions might be a worthwhile reason to learn the language.