It's rather embarrassing that we still have a macroscopic chunk of something as the standard kilogram. The other fundamental units are defined in terms of atomic processes, but for mass we have a macro standard and an atomic standard. Scandalous! (I'm sure when the Higgs boson is found that everything will sort itself out.)
What a wonderful set of resources for any teacher or student to explore. Here is what they have on Ben Franklin. Organized effectively and access to digitized documents that give you a window into his world.