Arrange grid elements into tiles. Works great if most of your columns match in width, and if you keep your wider ones on top...

grid-to-tiles.js

(function ($) {
  'use strict';
  $.fn.wmTiles = function () {
    var container = $(this),
      tiles = container.children(),
      arrange = function () {
        var places = [{
            t: 0,
            l: 0,
            w: container.width()
          }],
          p = 0,
          n,
          updateIndexes = function () {
            var i;
            for (i = 0; i < places.length; i += 1) {
              if (i === 0 || places[i].t < places[p].t) {
                p = i;
              }
            }
            switch (p) {
            case 0:
              n = p + 1;
              break;
            case places.length - 1:
              n = p - 1;
              break;
            default:
              n = places[p + 1].t < places[p - 1].t ? p + 1 : p - 1;
            }
          },
          fit = function (tile) {
            var w = $(tile).outerWidth(),
              h = $(tile).height();
            if (w < places[p].w + 3) {
              if (w < places[p].w) {
                places.splice(p + 1, 0, {
                  t: places[p].t,
                  l: places[p].l + w,
                  w: places[p].w - w
                });
                places[p].w = w;
              }
              $(tile).css({
                position: 'absolute',
                top: places[p].t,
                left: places[p].l
              });
              places[p].t += h;
              if (places[p].t > container.height()) {
                container.height(places[p].t);
              }
              updateIndexes();
              return true;
            }
            return false;
          },
          merge = function () {
            places[n].w += places[p].w;
            places[n].l = places[(p < n) ? p : n].l;
            places.splice(p, 1);
            updateIndexes();
          };
        tiles.removeAttr('style');
        if (tiles.css('float') === 'left') {
          container.height(0);
          $.map(tiles, function (tile) {
            while (!fit(tile)) { merge(); }
          });
        } else {
          container.height('auto');
        }
      };
    container.css({ position: 'relative' });
    arrange();
    $('img', container).load(arrange);
    $(window).resize(arrange);
  };
}(jQuery));