My pages have been used for reference, lots. My site has been at the same address for almost 10 years now, and I've done few major restructures of major sections, so link rot hasn't been all that much of an issue there.
Still, while I believe that my pages will stay on ibiblio indefinitely, I can't be sure.
I might copy the lot to dreamhost one of these years, and add a button that says "donate to keep this site online", which will work for as long as dreamhost is around, but for all I know dreamhost might be less permanent than ibiblio.
I might copyleft the site, after which it'll be here forever after ... but that won't happen while I'm still around myself, cos I like to brag about 200000+ visitors a month (on average), and 160000+ hits a day (currently - I'm on ibiblio's front page this month, that always shows in # of hits per day). If people were free to copy the lot the data would be all over the place, and I wouldn't be able to brag about site stats anymore.
Anyway, tricky problem, TA.