The process we outline is not elegant, but it does help you cover a lot of ground - you can find and analyze thousands of resources and root out the dead pages and sites quite quickly. I've been building 40+ links a month with this method for one of my clients, and selling BLB prospecting as a service to others. As I've said before, link rot is your friend.
CL Tools: Broken Link Builder
In some types of campaigns - value-add commenting and broken link building for example - you know the URL where your link will show up, assuming it gets published. And until today though I've always had to go, URL by URL, to see if my links went up. So I built a bulk backlink checker tool for my fellow link monkeys out there!