tells you if someone has removed a link from their site? So, say you do a link exchange, you type in the relevant info, and it can tell you if the other party has removed your link from their site. Not sure if its even possable, but i seem to keep getting caught up in 'Oneway link exchanges' lol
Making that as a WordPress plugin would be a poor solution. What you need is a script that checks the link and a cronjob to run that script every X hours/days...
There are crawl scripts and link management tools. But they don't work very well. They often return errors when the link is in fact working. Being the Net Police for all your links is a waste of time. While reciprocal linking is not entirely dead it's really a waste to monitor it. You can count on most of those links just going away over time.