Because I'm such a helpful, good-hearted person, I've performed an arduous service for Glenn -- despite his cruelty towards me. I'm sure it can be quite burdensome for someone of his stature to sort through his permalinks and remove the detrius, so I took it upon myself to do so for him (with the aid of a little scripting).
I found 14 blogs in his sidebar that have either not updated for over a month, or have announced their retirement. I didn't include sites that merely moved to new locations, or whose servers didn't respond. To the best of my ability, I can guarantee that these 14 blogs are no longer maintained. (Apologies in advance if that's not the case, for any one of you.)
If Glenn needs help finding new blogs to replace these, I'm sure I can help him think of some.