Abstract: The simplest of all statistical mechanical models is the Ising model which consists of spins, capable of being in two states, interacting with their nearest neighbours on some graph. This model was solved by Onsager in 1944. The simplest generalisations of the Ising model are the "spin models" where the only difference is that the number of spin states per site may be larger than 2. Sometimes these spin models also give invariants of knots and links. A beautiful example with 100 spin states per site, and the symmetry of the Higman-Sims finite simple group was discovered by Jaeger but finding more examples seems difficult.