add_action( 'admin_head-media-upload-popup', 'make_media_thumbs_bigger' );
function make_media_thumbs_bigger()
{
?>
<style>.media-item.preloaded{height:180px !important}</style>
<script type="text/javascript">
jQuery(document).ready( function($) {
$('#media-items img').each(function(){
$(this).attr('width','150').css('max-width','100%');
$(this).attr('height','150').css('max-height','100%');
});
$('#media-items .media-item.preloaded').each(function(){
$(this).css('height','380px');
});
});
</script>
<?php
}