Okay, well, it may not be so useful after all...though there are times when shouting "Die!" as loud as you can will clear a little breathing room in a crowded train car... Knowing a little Japanese is kinda cool, though, right?
Since this is an anime web site, I will only list some of the most interesting/useful bits of Japanese to help you understand some important elements of Japanese culture. I hope this will help you understand and appreciate some elements of anime more, especially if you enjoy watching subs. This also contains a dictionary of all the Japanese I use in my Sailor Moon fanfiction, where I have sprinkled random (not completely random...) Japanese words to add authenticity.