I think Roger's idea is very good but I'd prefer this option on the basis of posts. That is we'd have to decide with each post whether we want it to be permanent or to fade away after, e.g., 2 weeks.
So, if there'd be a lyrics request for 'My Willie sails over the ocean', Catspaw's post telling us what his personal association is when he reads 'Willie', my post telling that I might have the song at home but can't tell now and several others would fade away, while Stewie's post with the lyrics would stay.
With Mudcatters posting up to 65 posts a day that'd be a possibility to keep it functional for some more years.

Wolfgang