You might want to pop into some of your nearby vet clinics and ask the staff if they know of any clients who might be looking for a kitten. I only suggest that because it sounds like you have already checked out the shelters as an option. Some clinics have kittens and cats for adoption right there at their clinics and if you bring the little kitten with you, they might not be able to resist it and may take it in? This has happened a few times at the clinic I used to go to. As well, a staff member might take it. Vet staff tend to have quite the menagerie and a wee kitten might prove to be irresistable for one of them. Worth a try!
p.s. Don't forget to bring the kitten with you because seeing it will be more effective than 'hearing' a description of it.