The most widely available non-dairy nog is the Silk brand Soy Nog, although Vitasoy and Oregon Chai also have non-dairy nogs available. All three are good choices for anyone who is vegan, lactose intolerant or simply looking for a healthier - lower fat and lower calorie - alternative to traditional eggnog. I picked up Silk Nog, along with "light" and regular nogs (Rockview Farms brand from Trader Joe's) for an impromptu taste test.
The regular eggnog was the thickest and most yellow - no doubt to reassure the drinker as to the number of egg yolks - and the others were progressively less so. Personally, as I have a preference for thinner, uncooked eggnogs, I liked the "light" version better than the full fat. Neither had a strong egg flavor, but both had the feel of custard and a nice nutmeg-y taste, although there was an almost minty quality about them that seemed like it would work well with alcohol (I tasted all these plain). The Silk nog was not too sweet and was drinkably thin, making it more refreshing than either of the eggnogs. It also had a much milder taste to it, which I preferred. Overall? An eggnog aficionado is not going to be satisfied with the Silk nog and will probably enjoy the heavier stuff, but the Silk nog is tasty - and at only 90 calories and 2 grams of fat per serving, it's a holiday treat worth having.