Fork of the original gist https://gist.github.com/Cacodaimon/7309268 with improvements (support fot objects Not ony arrays and floats instead of just int values)

example.html

<!-- $scope.myList = [{name: 'Foo', total: 1}, {name: 'Bar', total: 2}, {name: 'Baz', total: 3}] -->
<span class="badge badge-success pull-right">{{myList|sumByKey:'total'}}</span>

SumByKey.js

angular.module('caco.feed.filter', [])
    .filter('sumByKey', function() {
        return function(data, key) {
            if (typeof(data) === 'undefined' || typeof(key) === 'undefined') {
                return 0;
            }

            var sum = 0;
            angular.forEach(data, function(obj, objKey){
                sum+= parseFloat(obj[key]);
            });

            return sum;
        };
    });