"Oooh, these ropes have had it, they're 8 years old and need replacing."
Get your arts and craft on http://www.roperugs.com/
But since you appear to live in Germany perhaps you can recycle them there?
I just donated a couple of old ropes to the local beavers and scouts groups, under the very clear understanding that they were not for climbing with any more. They were really happy to take them for knot practice, making bivis etc. Worth a shot?
I've got a hardly-used, ~15 year old rope (probably a 10.5 or 11 mm Mammut if memory serves) that's been sat in my parents' garage for most of that time. Is it any good to use for anything, or is it one for the rug weavers?
[Do unused ropes actually degrade over time?
Nylon supposedly loses upto 50% of strength over 10 years. Mountain Training guidance is to bin ropes even if unused and in original packaging at this age.