I had some Xtabentun, which is Mayan honey liqueur. Think of it as mead crossed with ouzo. Pretty nice as a sipping liqueur over ice.
Membrillo, which is this hard-to-find tequila/quince liqueur that's also suited to be sipped over ice. Sweet, but not TOO sweet.
There were, of course, the mandatory margaritas you are required to drink in Mexico or they revoke your tourist license. My favorites were the mango margaritas at La Buena Vida (which were like drinking a smoothie, though after a few I sure knew I wasn't DRINKING a smoothie) and the Don Julio Blanco margaritas at my hotel in Cancun. I also had some Don Julio reposado (which is a very smooth, peppery/oak tequila).
Havana Club anejo. This was done neat ala scotch. I got definite banana smells off of it. Awfully tasty.
Flor de Caña rum. I sampled some of the 5 year anejo (VERY smooth, banana smell off of it as well, but more pepper than the Havana Club), and had some of the 4 year white dry rum in a Cuba Libre (also very good, but white rum is for mixing, not drinking straight). I am bringing home a bottle of the 7 year rum (I think it ran me about $15). I am REALLY looking forward to cracking that open at some point.