Someone recently asked about the pine cone bird feeder project and what they could do if there's a child in the class with a peanut allergy.
There are a few alternatives here, including using tallow -- rendered beef fat, other nut butters like almond butter or macadamia spread, and using soy butter.
Using tallow is going to be a messy, greasy process, but the birds love it. This isn't recommended if you have children who cannot use cow products for religious reasons or if you have vegetarian/vegan children.
Soy butters are generally specially made for those with nut allergies, so this is your best bet. This can also be obtained pretty cheaply at Amazon or Wal-Mart (they carry their own brand, so very inexpensive).
Using other nut butters is an option, but you really need to be careful when choosing these since they may be processed in plants that also make peanut butter (even on the same equipment) or they may contain peanuts. Check the label for the allergy declaration before purchasing.
Soy butter would be the way I'd go.