What are some stiff neck remedies, in addition to using heat?

Meds and PT. For the pain and stiffness you could try nsaids (naproxen or ibuprofen) or acetaminophen. If stiffness has been present for more than a few days - some physical therapy may help.
Many. It depends on the cause of stiffness, various treatment modalities of physical therapy, muscle relaxants, Botox injection are available.