do it yourself calendar.

calendar.coffee

isSunday = (date) ->
  return date.getDay() is 0

nextDay = (date, days = 1) ->
  newDate = new Date(date.getTime())
  newDate.setDate(date.getDate() + days)
  return newDate

prevDay = (date, days = 1) ->
  newDate = new Date(date.getTime())
  newDate.setDate(date.getDate() - days)
  return newDate

nextMonth = (date) ->
  if date.getMonth() is 11
    return new Date(date.getFullYear() + 1, 0, 1)
  else
    return new Date(date.getFullYear(), date.getMonth() + 1, 1)

dayOfYear = (date) ->
  janFirst = new Date(date.getFullYear(),0,1)
  return Math.ceil((date - janFirst) / 86400000)

firstAvailableDate = new Date(2012,11,1)
year = firstAvailableDate.getFullYear()
month = firstAvailableDate.getMonth()

firstDayOfMonth = new Date(year, month, 1)
daysToDisplayPrior = if isSunday(firstDayOfMonth) then -6 else (if firstDayOfMonth.getDay() > 1 then -firstDayOfMonth.getDay() + 1 else 0)
firstMondayInCalendar = null
if month is 0
  firstMondayInCalendar = new Date(year - 1, 12, daysToDisplayPrior)
else
  firstMondayInCalendar = new Date(year, month, daysToDisplayPrior)

lastDayInMonth = prevDay(nextMonth(firstDayOfMonth))
daysInMonth = dayOfYear(lastDayInMonth) - dayOfYear(firstDayOfMonth)
daysToDisplay = daysInMonth + Math.abs(daysToDisplayPrior)
weeksToDisplay = Math.ceil(parseFloat(daysToDisplay / 7, 10))

results = []
for week in [0...weeksToDisplay]
  datesInWeek = []
  for wday in [1..7]
    datesInWeek.push nextDay(firstMondayInCalendar, week * 7 + wday)
  results.push datesInWeek

calendar.rb

require 'date'

year = 2012
month = 12
first_day_of_month = Date.new(year, month, 1)

days_to_display_prior = (first_day_of_month.sunday? ? -6 : (first_day_of_month.wday > 1 ? -first_day_of_month.wday : 1))

first_monday_in_calendar = if month - 1 == 0
  Date.new(year - 1, 12, days_to_display_prior)
else
  Date.new(year, month - 1, days_to_display_prior)
end

7.times.map { |wday| first_monday_in_calendar.next_day(wday) }

last_day_in_month = first_day_of_month.next_month.prev_day
days_in_month = last_day_in_month.yday - first_day_of_month.yday
days_to_display = days_in_month + days_to_display_prior.abs
weeks_to_display = weeks_to_display = (days_to_display.to_f / 7).ceil

weeks_to_display.times.map { |week|
  7.times.map { |wday|
    first_monday_in_calendar.next_day(week * 7 + wday).strftime("%Y-%m-%d")
  }
}