Combinatory Logic?
This looks pretty cool:
http://plato.stanford.edu/entries/logic-combinatory/
Again I got this from @CompSciFact. I don't have time to read much of it at the moment; I'm currently trying to wrap my mind around Paraconsistant Logic.
I really need to get a good, modern book on logic. I've heard that Logical Pluralism might be a good introduction ...