If you are looking for a powdered version - Jarrow Formulas makes a whey protein powder that is sans artificial sweeteners (no nuts, gluten or egg, does have milk and soy ingredients).

Both Boost and Ensure have high protein versions that are nut free.  DS1 loves them but I tend to find them sicky sweet.  If you want to call for yourself, I found them to be really helpful (we avoid gluten and egg for DS1 but knew Macabre needed info during a hard time so I called for her). 

DS1 also uses Boost Breeze (we have to order from Amazon.com) which are juice boxes.  Probably not the highest protein you are looking for, I discovered them after a personal surgery and found them to be really tasty.  DS1 needed help in the calorie and protein department so we ordered them for him.  Expensive but worth it for him.

DS has had Boost and hmmmm one other.  I have got to head to work, but if someone can dig up the first thread about my son's accident, YKW posted incredibly helpful and detailed information about a couple of them.  She was so very sweet and kind and made those calls after my son had a horrible accident last summer and relied on those drinks for a while. 

He is allergic to peanuts.

Does anyone know of any high protein drinks that are safe for someone with nut allergies besides Pediasure?