Linking your Coinbase account with your Mint account is not as obvious as it may seem… believe me I tried jumping into the Coinbase settings and generating the API key with settings that I thought would work and after numerous failed attempts swallowed my pride and searched for a solution directly from Coinbase support. The steps outlined in the link below worked immediately.
Important! Once you create the API, a popup will appear which displays your API Key and API Secret. Remember to copy and store this someplace safe and secure. You’ll need those when adding your Coinbase account in Mint.
I will note that after successfully linking my Coinbase account with Mint my account showed up under the “Investments” category. Which is fine as I’m just toying with the whole Bitcoin thing for educational purposes. However perhaps in the future (when Bitcoin becomes more standard) I would like to see the option in Mint to classify Coinbase as an “Investments” or a “Cash” account depending on the user.
Read more about Bitcoin here: http://www.couchbaby.com/bitcoin/