Appears userscripts.org is down. This was the place I grabbed all my Greasemonkey scripts from so I'm a bit surprised (I'm also apparently late to the game, it's been down for a while.) Fortunately the Ghacks page lists some alternatives, including userscripts-mirror.org and greasyfork. Lucky for me the mirror had a link to the latest YouTube Center (the grid layout for my subscriptions makes this well worth installing.)