Nut butters (almond, walnut, and pecan are awesome)
Unsweetened coconut flakes
Eggs… hard boiled… maybe wrapped in bacon…
Canned tuna (I mix in a little bit of German mustard)
Sliced, uncured deli meat
Sliced veggies (celery, carrots, bell pepper, cucumbers)
Pickles (check the ingredients)
The occasional Larabar (no added sugar or sweeteners, but watch the carbs on these as they are mostly dried fruit)
Most of these things don't require a whole lot of skill or prep time, either. A few plastic baggies, two hands and a couple of minutes to portion things out. I'll put a little bit of emphasis on the portioning out part of that. I could just keep a 12-16 oz. bag of almonds at my desk... but I know that I am more than capable of eating 4+ servings if they are just sitting there and I am mindlessly grazing on them. But if I portion that bag out into 1 oz. baggies before the week starts, I know I won't OD on them.
Let me know if there is an easy, paleo/primal snack that I can add to my lunch bag rotation as I am always looking for new ideas.