Sgt_Kickaxe - 7:33 pm on Nov 7, 2010 (gmt 0)
Two years ago I spied a .edu link that lead to one of my recently out of business competitors. I contacted the site author at the university and politely told him the link had gone cold and kindly offered a page on my site as a suitable replacement. He thanked me and I got the link.
If your site is link worthy this is a great method. I don't recommend trying to get webmasters to remove valid links but keep an eye out for sites that have gone offline and see if any freshly broken links would be worth getting.