JavaScript Bookmarklet to add-up all the estimated checklist items on a card in Trello.

trello-checklist-sum.js

var $lists=$(".checklist");
$.each($lists, function( key, value ) {
 
  var $lName = $(value).find(".checklist-title h3");
  var $lNameInput = $(value).find(".checklist-title input");
 
  var $items = $(value).find(".checklist-item");
  var $tot = 0;
  $.each($items, function(key, value) {
      var $itemText = $(value).find(".checklist-item-details-text");
      var $itemEst = $itemText[0].innerText.match(/\(\d+\.?\d*\)/g);
      if ($itemEst) {
        $itemEst = new Number($itemEst[0].replace("(", '').replace(")", ''));
        if (!isNaN($itemEst)) {
          $tot += $itemEst;
        }
      }
   });
   $lNameUp = $lName[0].innerText.match(/^[^\(]*/i);
   $lNameUp += ' (' + $tot + ')';
   $lName[0].innerText = $lNameUp;
   $lNameInput.val($lNameUp);
});

Gist updated for recent Trello changes

well done! Could you please advise how to aggregate now checklists to card name?

Then Scrum for Trello plugin will be compatible