I noticed at the weekend, that a simple mistake (several months ago), has led to a chunk of one of my sites being inaccessible ever since... My embarrassment only just outweighed my frustration! Fixing the mistake took seconds, and released a lot of content, but it demonstrates just how easy it was to make the mistake. Since then, I've had a look at some link checking tools and stumbled across this Fast Link Checker, which allows 30 days of free trial - easily enough time to quickly check your links are in order.