Help weeding dead feeds

My feeds have piled up over the years. I know quite a few of them are dead as doorknobs, but clicking through each and every feed for a last-updated date takes forever, so I never get around to weeding them.

I would be thrilled if Newsblur could:

* automatically check sites associated with inactive feeds to see if there’s a newer feed (sites are really bad about redirecting, as I’m sure everyone knows)

* on request, make a list of feeds that haven’t seen activity in a long time, and make it easy to unsub from most/all of them at once. (One year would do it for me, but I’m not sure that’s the optimal length. Thoughts?)