I'm wondering - what data is available to the Ethereum smart contracts? I stumbled upon some tutorials on how to write the contracts that give some indication as to a few examples of the data is available, but a more comprehensive list / wiki page would be useful to have for reference.
I'm not sure if this is actually complete, but the solidity language runtime exposes most of the useful stuff:
So basically, only existing state and new data entered as arguments from new signed transactions. This means "real world" data mostly has to come from some kind of oracle mechanism.