tedster - 9:25 pm on Nov 28, 2010 (gmt 0)
And the shame of it is that a few links gone bad will NOT cause a penalty on the linking site. I have a client who maintains a large set of references and we review it quarterly. This used to be called a "hub", although I don't hear that word much anymore.
Every quarter we find several links at review time whose target URL has gone bad and we fix them - this has never caused a ranking problem as far as I can see.