CoffeeScript version done with js2coffee and some manual formatting ^ ^ )

Bacon.UI.coffee

nonEmpty = (x) ->  x and x.length > 0
isChrome = navigator.userAgent.toLowerCase().indexOf("chrome") > -1
Bacon.UI = {}
Bacon.UI.textFieldValue = (textfield, initValue) ->
  getValue = ->
    textfield.val()
  autofillPoller = ->
    if textfield.attr("type") is "password"
      Bacon.interval 100
    else if isChrome
      Bacon.interval(100).take(20).map(getValue).filter(nonEmpty).take 1
    else
      Bacon.never()
  textfield.val initValue  if initValue isnt null
  textfield.asEventStream("keyup input").merge(textfield.asEventStream("cut paste").delay(1)).merge(autofillPoller()).map(getValue).toProperty(getValue()).skipDuplicates()

Bacon.UI.optionValue = (option) ->
  getValue = ->
    option.val()
  option.asEventStream("change").map(getValue).toProperty getValue()

Bacon.UI.checkBoxGroupValue = (checkboxes, initValue) ->
  selectedValues = ->
    checkboxes.filter(":checked").map((i, elem) ->
      $(elem).val()
    ).toArray()
  if initValue
    checkboxes.each (i, elem) ->
      $(elem).attr "checked", initValue.indexOf($(elem).val()) >= 0

  checkboxes.asEventStream("click").map(selectedValues).toProperty selectedValues()

Bacon.UI.ajax = (params) ->
  Bacon.fromPromise $.ajax(params)

Bacon.Observable::awaiting = (response) ->
  @map(true).merge(response.map(false)).toProperty(false).skipDuplicates()

Bacon.EventStream::ajax = ->
  this["switch"] Bacon.UI.ajax

Bacon.UI.radioGroupValue = (radioButtons, init) ->
  if init?
    radioButtons.each (i, elem) ->
      $(elem).attr 'checked', true if elem.value is init
  else init = radioButtons.filter(':checked').first().val()
  radioButtons.asEventStream('change').map((e) -> e.target.value).toProperty init

Bacon.UI.checkBoxValue = (checkbox, initValue) ->
  isChecked = ->
    !!checkbox.attr("checked")
  checkbox.attr "checked", initValue  if initValue isnt null
  checkbox.asEventStream("change").map(isChecked).toProperty(isChecked()).skipDuplicates()

Bacon.UI.hash = (defaultValue) ->
  defaultValue = ""  if defaultValue is undefined
  getHash = ->
    (if !!document.location.hash then document.location.hash else defaultValue)
  
  $(window).asEventStream("hashchange").map(getHash).toProperty(getHash()).skipDuplicates()

Update to radioGroupValue. Fixes an issue I found with the previous version.

Bacon.UI.radioGroupValue = (radioButtons, init) ->
  if init?
    radioButtons.each (i, elem) ->
      $(elem).attr 'checked', true if elem.value is init
  else init = radioButtons.filter(':checked').first().val()

  radioButtons.asEventStream('change').map((e) -> e.target.value).toProperty init

Done )