To cite snp.plotter in publications use:

Luna A, Nicodemus KK (2007). snp.plotter: an R-based SNP/haplotype association and linkage disequilibrium plotting package. Bioinformatics, 23, 6:774-6.

Corresponding BibTeX entry:

  @Article{,
    title = {snp.plotter: an R-based SNP/haplotype association and
      linkage disequilibrium plotting package.},
    author = {A. Luna and K.K. Nicodemus},
    journal = {Bioinformatics},
    volume = {23},
    number = {6},
    year = {2007},
    pages = {774-776},
    month = {Mar},
    url = {http://cbdb.nimh.nih.gov/~kristin/snp.plotter.html},
  }