Capital One foreign transaction alerts are the best!
I use Capital One exclusively when traveling in Europe because of the excellent exchange rate and no added fees. But the feature I recently have become addicted to is the foreign transaction alert which is an e-mail showing the US$ conversion. Most of the time the e-mail will arrive to my Blackberry when I am still standing at the cash register! I just find this to be very useful to someone on the road spending foreign currency.