Have you listed them on http://Petfinder.com? Is there a Pet Talk person who could foster them until they can find a forever home? As a person who deals with allergies on a daily basis, I feel very bad for you, and know this is a gut-wrenching decision for you.

You'll be in my prayers, I'm on the wrong side of the country (not to mention my own massive cat allergies) to help, but I hope a solution can be found.