Where do the majority of Bitcoin transactions take place? I'm new to Bitcoin and am trying to wrap my head around where and when bitcoins are used.  I understand that Bitcoin is accepted by a lot of legitimate websites (now reddit, wordpress, etc) for digital goods or services and there are also online market places that sell physical goods.  There also seems to be a lot of illicit activity transacted in Bitcoins since it is (fairly) anonymous.  

My questions are basically:


What types of things is bitcoin buying and for what percentage of the total transaction volume are these things responsible?
How much of the transaction volume is responsible for physical or digital goods as opposed to just bitcoin trading?
Are these markets sustainable or are they likely to disappear (i.e. the illicit activity)?
Because bitcoin is a pseudonymous digital currency, there are no hard statistics available.

Because one popular service, SatoshiDICE, uses static Bitcoin addresses as the wagering mechanism for the players of its online "Dice" game, the amount of activity related to them can be measured.  It currently represents the majority of bitcoin transactions (but not value) that crosses the network.

Currently the Bitcoin network is hitting about 50,000 transactions per-day.  Some of these transactions will be performed for the purpose of mixing coins to protect the privacy of the sender.

By far the biggest interest in Bitcoin to-date (going from an educated guess) has been for speculative and investment purposes.  As such a large amount of the activity is transfer of funds to and from (and between) exchanges.

The ratio of this type of activity versus commerce involving digital and physical goods will heavily favor the speculative/investment but by to what degree is unknown as that data is not shared by the private parties who trade these goods and services.  If it were a ratio of 25:1, that would not be surprising to me.

While the ratios may change over time as bitcoin gains traction for more mainstream use, any use established at this early time will likely continue -- it will just represent a shrinking slice of a rapidly growing pie.