<style>
.ui-select {
  background:#fff;
  position:absolute;
  top:10px;
  right:10px;
  z-index:100;
  padding:10px;
  border-radius:3px;
  }
</style>

<div id='filters' class='ui-select'>
  <div><input type='checkbox' checked=checked class='filter'
             name='filter' id='fast-food' value='fast-food'/><label for='fast-food'>fast-food</label></div>
  <div><input type='checkbox' checked=checked class='filter'
             name='filter' id='bicycle' value='bicycle'/><label for='bicycle'>bicycle</label></div>
  <div><input type='checkbox' checked=checked class='filter'
             name='filter' id='bar' value='bar'/><label for='bar'>bar</label></div>
</div>
<div id='map'></div>

<script>
L.mapbox.accessToken = '<your access token here>';
var map = L.mapbox.map('map', 'mapbox.dc-markers');
var filters = document.getElementById('filters');
var checkboxes = document.getElementsByClassName('filter');

function change() {
    // Find all checkboxes that are checked and build a list of their values
    var on = [];
    for (var i = 0; i < checkboxes.length; i++) {
        if (checkboxes[i].checked) on.push(checkboxes[i].value);
    }
    // The filter function takes a GeoJSON feature object
    // and returns true to show it or false to hide it.
    map.featureLayer.setFilter(function (f) {
        // check each marker's symbol to see if its value is in the list
        // of symbols that should be on, stored in the 'on' array
        return on.indexOf(f.properties['marker-symbol']) !== -1;
    });
    return false;
}

// When the form is touched, re-filter markers
filters.onchange = change;
// Initially filter the markers
change();
</script>