Adding Progress Bar to '*apply' Functions
Peter Solymos [aut, cre], Zygmunt Zawadzki [aut]
A lightweight package that adds
  progress bar to vectorized R functions
  ('*apply'). The implementation can easily be added
  to functions where showing the progress is
  useful (e.g. bootstrap). The type and style of the
  progress bar (with percentages or remaining time)
  can be set through options.
  Supports several parallel processing backends.