We sort of have the opposite situation going on...
My little guy's preschool is not peanut free (no affected children), but I am severely allergic to peanuts. I've grown up to be very careful, but even so, there have been more incidents of accidental peanut contact in the past year than in probably the last 10 years prior combined.
If my husband is packing his lunch, he will often put a pb&j in his box, but he has to be extremely careful to wipe all the counters down and thoroughly clean everything that came in contact (can't just put the knife in the sink, kwim?).
Our church nursery is peanut free due to my allergy.

I feel bad, but I don't feel so bad after a few incidents where kids came in with peanut butter crackers and touched me which led to the oils migrating into my eyes and causing my eyes to swell shut.
So... when I pack his lunch (which we've been doing for about 4 months), here's what I do and some ideas for you.
First of all, a big part of our lunch routine is this box...
http://www.laptoplunches.com/
It's a lead free, phthalate free bento style box. It seriously encourages you to pack small portions of healthy foods. And... it's waste free!
I get a lot of my ideas from here....
http://flickr.com/groups/laptop_lunches/pool/
I tend to put one carb such as some pasta salad (make it Sunday night and it should last through maybe Wednesday morning in the fridge) from rotini or elbows, throw in some cut up cucumber, sliced grape tomatoes, any other veggies you've got laying around, and a little bit of greek or italian dressing. Other times, I'll put a turkey sandwich, but he's not a huge fan of that. Or even just some whole wheat crackers.
Sometimes I put in colby-jack slices or cubes. I almost always put in fruit of some kind. Sliced strawberries, blueberries, grapes, mandarin oranges, etc... Then I pack a few baby carrots and some ranch dressing in the tiny lidded container. He's a big fan of regular salad too, so if I have some lettuce on hand, I'll stuff that in there with grape tomatoes and some dressing in the tiny container.
Sometimes I'll put yogurt in the large lidded container, with a little bit of granola on the side to pour on top.
I usually include a little treat like a low fat/sugar cookie and there are some great organic, low-sugar water based juice pouches at Sams made by HonestKids (HonestTEA). You get like 24 for $9. If I'm out of those, I'll fill a stainless Sigg or Kleen Kanteen with watered down grape or cranberry juice.
When Winter rolls around, I'll pick up a stainless thermos and maybe put leftovers in it, but for right now we're sticking with all the in-season goodies that are fresh. His lunch goes into a refrigerator at school, but they are not capable of heating anything. With the Laptop Lunch box, there is an icepack that goes into the available carry-case and that may keep things cool if they don't refrigerate.
Anyways... we love his lunch box because it really challenges us to pack variety and small, fresh foods.