Lottery number generator
A min-max pair would be slightly better represented using a Range.  In fact, starting with Ruby 1.9, rand can accept a range.

The loop can be written a bit more succinctly.

The pretty-printing function should also be written in one line instead.

lower_case is a more conventional naming convention.  An explicit return is not necessary, as the code returns the last value anyway.

def get_random_numbers(range, count=1)
  array = []
  while array.length &lt; count
    n = rand(range)
    array.push(n) unless array.include?(n)
  end
  array
end

def pretty_print(array)
  puts array.join("\t")
end

pretty_print(get_random_numbers(1..49, 6)