font awesome 4 animated loading spinner
<i class="fa fa-spinner fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-circle-o-notch fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-refresh fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-cog fa-spin fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>
<i class="fa fa-spinner fa-pulse fa-3x fa-fw"></i>
<span class="sr-only">Loading...</span>