I randomly picked up a round bar of Taza's Chocolate Mexicano Cinnamon in SF during my last visit, not really expecting too much. I just opened the package and, man, this stuff is really good. So good that I'm having a hard time putting it down. It's somewhat similar to the Mexican drinking chocolate bars (my standby was Mayordomo, but when couldn't get that anymore, I switched to La Soledad), but much more refined and less sweet. Yet, it still has that rustic quality with a crunch of sugar crystals and whiff of cinnamon. I usually make hot chocolate, but I figured I'd give Taza's a try as an eating chocolate and I'm glad I did: the chocolate has a deep, complex taste. They must be sourcing some quality beans. I'm thinking that it has a very good chance of producing a superior cup of Mexican hot chocolate, as the sweetness of other brands is getting a bit cloying the older I get.
It's not cheap: $4.99 for the bar I bought, though the website lists $3.95. The website also states that Taza is the only US maker of 100% stone-ground chocolate. Taza is located in Somerville, MA.