Genetic variation in humans and model organisms (measured by SNPs)
SNP Density

Human = ~1.18 SNPs per kbases


  Based on CgsSNP, the average numbers of SNPs per 10 kb was 8.33, 8.44,
  and 8.09 in the human genome, in intergenic regions, and in genic
  regions, respectively.


Source: Investigating single nucleotide polymorphism (SNP) density in the human genome and its implications for molecular evolution. by Zhao Z, Fu YX, Hewett-Emmett D, Boerwinkle E.

Drosophila melanogaster = ~0.02 SNP per kbases


  FLYSNPdb provides high-resolution single nucleotide polymorphism (SNP)
  data of Drosophila melanogaster. The database currently contains 27
  367 polymorphisms, including >3700 indels (insertions/deletions),
  covering all major chromsomes. These SNPs are clustered into 2238
  markers, which are evenly distributed with an average density of one
  marker every 50.3 kb or 6.6 genes.


source: FLYSNPdb: a high-density SNP database of Drosophila melanogaster

Mouse(Mus musculus) = ~0.2 SNP per kbases

Source: Genome-wide single-nucleotide polymorphism
analysis defines haplotype patterns in mouse