I didn't read through all the responses, so please excuse this if it's repetitive!
My cousin's son had a milk allergy (the good news is that he, like many kids, outgrew it around age 5!)...It was frustrating for them because most "non-milk" foods were marketed towards lactose-intolerant individuals, not dairy-allergic. Therefore, when she bought "Veggie Slices" (marketed as soy cheese), it still contained milk proteins, so it didn't work for her son.
anyway, I'm not sure where you live or how available these products are, but try the KOSHER section. For those reading this who are not Jewish or who are unfamiliar with this, one of the important rules of keeping Kosher is that you can't eat dairy products together with meat products (meaning red meat, chicken, ...but for some reason, fish doesn't count as meat!)... Anyway, there's nothing special about the actual foods except that they are categorized as either "dairy", "meat", or a third category called "Pareve", which means neither dairy nor meat. In other words, it becomes very easy to tell which foods have dairy and which foods don't.
So if you find a Kosher product (most often marked with a circled-U or a triangled-CRC, etc), it will say if it is dairy... the circled-U symbol will likely have a "D" next to it. The easiest way to avoid this is to look for foods marked "PAREVE", which means, BY DEFINITION, THEY ARE DAIRY FREE! There can be no hidden milk proteins!(The purpose is that those who keep Kosher know that they are alowed to eat these foods with meat.)
One "Kosher Pareve" brand I will mention is DR. PRAEGER'S. It's a line of frozen prepared foods that are all made from natural/healthy ingredients (you can understand all the words in the ingredient list!). There are some fish products (fish sticks, salmon burgers, etc.), but most are vegetarian/vegan: diffrent flavors of Veggie burgers, broccoli pancakes, spinach pancakes, potato pancakes, etc. It's a great way to get veggies into the kids, and the food is certified Kosher Pareve. I usually find his stuff in the Natural Foods frozen section of Jewel/Whole Foods. I think you can also order food online. Try: www.drpraegers.com (I swear, I am NOT involved with this company at all! I just love the products - my 3 year old son and 14 month old twin daughters LOVE the stuff!)
Hope this helps!