Please let me know if you have any ideas. My specialities lie in data mining, text visualization, machine learning, and security informatics
Right now there is a huge problem with price discovery. For instance, a little over two weeks ago, a $50 price was a lofty goal. Today $90 seems appropriate. Obviously, either they were wrong two weeks ago or we are wrong today.
One of the difficulties in determining Bitcoin's value is there is little useful data. So things like "Number of /r/bitcoin Reddit users online simultaneously", or "Google trends" numbers are considered for speculation instead of things like a true "economic activity" metric.
This is a problem for governments where the economy operates significantly using cash (which could be used anonymously) and it is a challenge that will be returning thanks to Bitcoin. Knowing how much economic activity is occurring with Bitcoin is going to become more and more valuable. Right now so little of Bitcoin's value is based on the true demand due to economic activity that this metric is pretty much worthless today. For instance, the largest Bitcoin payment processor is BitPay, which just reported they crossed the $2 million threshold for March. Two million dollars. Square does that much business for their merchants in a few hours, and they are just a tiny blip in the payment card industry.
I don't know what approach would allow an economic activity metric to be measured accurately. Governments can mandate reports (tax returns), and industry councils can request completion of periodic surveys from their members. Bitcoin has neither ... for now. Bitcoin does have a blockchain in which most bitcoin-denominated transactions appear in (not all do though ... a payment handled as a withdrawal from a Mt. Gox customer's EWallet to a Mt. Gox merchant might be handled internally by Mt. Gox's spend transaction, for example).
This is one area where a site spider could determine roughly how many sites accept bitcoin and based on how much traffic each site gets determine some rough trends that would be useful in determining valuations.
If this information were to be valued it could probably be sold privately (e.g. to subscribers), or maybe there is even a way it could be shared publicly.
Either way, multiple people will eventually be working on the "how to measure the Bitcoin economy" problem, but so far there hasn't been enough of an economy that many are working on it today. That will be changing.
