Trello Burndown Google Apps script modified from http://echobehind.wordpress.com/2012/06/28/create-your-own-burndown-chart-using-trello-api-and-google-apps-script/

TrelloBurndownGoogleAppsScript

function trelloFetch(url) {
  var key = "your_trello_API_key",
      api_endpoint = "https://api.trello.com/1",
      member_token = "your_member_TOKEN"; 
  var completeUrl = api_endpoint + url + "?key=" + key + "&token=" + member_token;
  
  var jsonData = UrlFetchApp.fetch(completeUrl);
  var object = Utilities.jsonParse(jsonData.getContentText());

  return object;
}

function getActiveSprintData(active_sprint_id) {
  var active_sprint_lists,
      active_sprint_cards,
      done_list_id,
      fires_done_list_id;
  var points = [],
      number_of_stories = 0,
      points_all = 0,
      points_left = 0,
      points_fires = 0,
      points_fires_left = 0,
      points_fires_done = 0,
      points_done = 0;
   
  active_sprint_lists = trelloFetch("/boards/" + active_sprint_id + "/lists/");
  active_sprint_cards = trelloFetch("/boards/" + active_sprint_id + "/cards/");
  
  for (var i=0; i<active_sprint_lists.length; i++) {
    if (active_sprint_lists[i].name == "Done")
      done_list_id = active_sprint_lists[i].id;
    if (active_sprint_lists[i].name.indexOf("Fires") != -1)
      fires_done_list_id = active_sprint_lists[i].id;
  }
  
  for (var i=0; i<active_sprint_cards.length; i++) {
    var regex = /\((\d+)\)/;
    var story_point = active_sprint_cards[i].name.match(regex);
    
    story_point = story_point ? parseInt(story_point[1]) : 0;
    points_all += story_point;
    number_of_stories++;
    
    /* count fires separately and remove them from points_all */
    if (active_sprint_cards[i].labels[0]) {
      for (var j=0; j<active_sprint_cards[i].labels.length; j++) {
        if (active_sprint_cards[i].labels[j]['name'] == "Fires") {
          points_fires += story_point;
          points_all -= story_point;
        }
      }
    }
    
    /* count finished stories */
    if (active_sprint_cards[i].idList == done_list_id) {
      points_done += story_point;
    }
    
    /* count finished fires */
    if (active_sprint_cards[i].idList == fires_done_list_id) {
      points_fires_done += story_point;
    }
  }
  
  points_left = points_all - points_done;
  //points_fires_left = points_fires - points_fires_done;
  points[0] = [points_left, points_fires, points_done, points_fires_done, points_all];
  
  return points;
}

/* fetch data from Trello and append it to Spreadsheet */
/* Column 'J' must have the following stuff for this to work:

Sprint # // Sprint number – whatever you want
Name of sprint // Sprint name - whatever you want
21.6.2012 // Sprint start date – in that format
5.7.2012 // Sprint end date - in that format
board_id // board_id. Get it from your board URL format which 
             looks like this https://trello.com/b/[board_id]/new-board

*/
function fetchData() {
  var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets(),
    active_sheet = "",
    sprint_info_column = 10;
  
  for (var i=0; i<sheets.length; i++) {
    if (sheets[i].getName().indexOf("#active") != -1)
      active_sheet = sheets[i].getName();
  }

  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(active_sheet);
  
  var data,
      baserow = 2,
      basecolumn = 1,
      datenow = new Date(),
      today = datenow.getDate() + "." + (datenow.getMonth()+1) + "." + datenow.getYear(),
      active_sprint_id = sheet.getRange(5, sprint_info_column).getValue();
  
  while (sheet.getRange(baserow, basecolumn).getValue() != "") {
    if (sheet.getRange(baserow, basecolumn).getValue() == today)
      break;
    baserow++;
  }
  
  data = getActiveSprintData(active_sprint_id);
  sheet.getRange(baserow, basecolumn + 1, 1, 5).setValues(data);
}

/* generate dates from start to end of a sprint */
function sprintStart() {
  var sheets = SpreadsheetApp.getActiveSpreadsheet().getSheets(),
    active_sheet = "",
    sprint_info_column = 10;
  
  for (var i=0; i<sheets.length; i++) {
    if (sheets[i].getName().indexOf("#active") != -1)
      active_sheet = sheets[i].getName();
  }

  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(active_sheet);
  
  var baserow = 2,
      basecolumn = 1;
  var start_date_array = sheet.getRange(3, sprint_info_column).getValue().split("."),
      end_date_array = sheet.getRange(4, sprint_info_column).getValue().split(".");
  var start_date = new Date(start_date_array[2], parseInt(start_date_array[1])-1, parseInt(start_date_array[0])),
      end_date = new Date(end_date_array[2], parseInt(end_date_array[1])-1, parseInt(end_date_array[0]));
  var current_date = start_date;
  
  // generate headers
  sheet.getRange(baserow - 1, basecolumn, 1, 6).setValues([['Date', 'Score', 'Fires', 'Score done', 'Fires done', 'Total score']]);

  // generate dates
  while (current_date.getTime() != end_date.getTime()) {
    sheet.getRange(baserow, basecolumn, 1, 1).setValue(current_date.getDate() + "." + (current_date.getMonth()+1) + "." + current_date.getYear());
    current_date.setDate(current_date.getDate() + 1);
    baserow++;
  }
  sheet.getRange(baserow, basecolumn, 1, 1).setValue(current_date.getDate() + "." + (current_date.getMonth()+1) + "." + current_date.getYear());
  
  // create 5min Trigger
  ScriptApp.newTrigger("fetchData").timeBased().everyMinutes(5).create();
  
  // create end Trigger
  var end_date_trigger = new Date(end_date_array[2], end_date_array[1] - 1, end_date_array[0], 10);
  ScriptApp.newTrigger("sprintEnd").timeBased().at(end_date_trigger).create();
}

/* remove all triggers when it comes to the end of a Sprint */
function sprintEnd() {
  var triggers = ScriptApp.getScriptTriggers();
  for (var i = 0; i < triggers.length; i++) {
    ScriptApp.deleteTrigger(triggers[i]);
  }
}