How many transactions have been included into the blockchain? This website shows the number of bitcoin transactions per day, but I want to know how many there are total. How can I do this?
As of block 210000, the total number of transactions in the chain is 9344662.

Version 0.8 of the reference client keeps track of this number, and reports it for every connected block in debug.log. I just copied the number from the debug.log of a node running pre-release code.