PBS
Pbs Learning Media: Mendel's Laws of Genetic Inheritance
This interactive activity, adapted from the Dolan DNA Learning Center, uses Punnett squares to illustrate Mendel's laws of inheritance and how a particular gene combination results in a 3-to-1 ratio of dominant-to-recessive traits.
Khan Academy
Khan Academy: Variations on Mendel's Laws (Overview)
Article reviews Mendel's basic model of inheritance then provides an overview of variations on Mendel's laws, including multiple alleles, incomplete dominance, co-dominance, pleiotropy, lethal alleles, sex linkage, genetic interactions,...
University of Hamburg
University of Hamburg: Deviations From Mendelian Laws And: What Is the Meaning of Dominance?
Upper level discussion of several of Mendel's experiments and laws.