Software Must Haves

Both my parents and grandparents were very into music, so although I am comparitively young, my listening tastes are truly expansive. I even like rap which I find most of you hate. Anyway, I finally have my system in a state that I truly enjoy, and probably won't be upgrading for a while (yeah right). Now I need more software. So...If you had to make a list of must have recordings, what would they be. Now I'm not talking about some obscure oboe player from Sri Lanka that "is 2 die 4" I'm talking about albums like "Kind of Blue" , pieces of music that anyone with a good collection should have. I have what I think are a lot of them, but I would love some other opinions.