Just enabled discovery for my blogroll based on the OPML blogroll spec. While technically not part of the spec, I also have similar collections for podcasts and YouTube. I've added those as well.
<head>
<!--...-->
<link rel="blogroll" type="text/xml" title="Luis Quintanilla's Blogroll" href="/collections/blogroll//index.opml">
<link rel="youtuberoll" type="text/xml" title="Luis Quintanilla's YouTube Roll" href="/collections/youtube//index.opml">
<link rel="podroll" type="text/xml" title="Luis Quintanilla's Podroll" href="/collections/podroll//index.opml">
<!--...-->
</head>
youtuberoll doesn't really roll off the tongue, but I'm hesitant to call it videoroll or vidroll. My concerns mainly come from the fact that YouTube != video.
Ideas welcome!