Schokinag Dark Drinking Chocolate was a favorite of mine as well. It required a good amount of stirring to get the product to disperse. The sad news is that Schokinag discontinued it, due to lack of popularity.

Callebaut chocolate shaved up and melted with hot milk is good as well, if you add some natural sugar (Sugar in the Raw etc)

In San Francisco, there is a place along the piers that has a great drinking chocolate as well. Really fudgy, thick, yet smooth. Their products seem kind of arty design looking. TCHO

One of the best I've had while traveling is San Churro but AFAIK it's only available in Australia at their shops. Good stuff with a good touch of spice to it. I can attest that there are a few thickeners in the product to give it that 'rich' appeal.

Then there is one I discovered that comes from France, but I'm going to be selfish and not share the name, as it's just something I want all to myself