Old, new, borrowed, blue, right? Technically, there's also supposed to be "a sixpence in your shoe," but I'll have enough shoe comfort problems that I'll probably avoid that.
I have had several people ask me if I'm going to do this ritual, and what I'll do for it, and the answers are "yes," and this:
Old: My freshwater pearl necklace my uncle gave to me for my 8th grade graduation.
New: My wedding dress! My mom got married in jeans, so that wasn't an option.
Borrowed: My mom's pearl earrings (because she has real ones, and I don't).
Blue: My garter has a tiny blue bow on the inside, meant as a "something blue."
It's a pretty neat feeling to know that I'm going to be a small part of an old tradition that many brides before me have done. A little bit of history carried with me for a little bit of luck.