I'd suggest you lease a server and start building some minisites. Get some IBLs going. Get some traffic going. Then, maybe, you'll find some buyers.
You can list 'em till ICANN freezes over but unless they are gems (all mined a long time ago), or you got lucky predicting the future (it could happen, about as often as winning the lottery) the only way they will ever sell is someone comes to you because they just like the domain.
The frequency of the latter is about 1 in 9,375 domains and in those cases the offer will usually be <$1,000.
List 'em everywhere (just search for "domain forum") they allow you to list 'em and then settle in for a long winter's nap.
I have sold one for $1000 US
About 20 for $300 each
and was offered $7500 for another but turned it down because I want it for myself.
I have a number of really cool domains I am holding on to for possible personal or business use. Most of them I registered 5 or 6 years ago when there were still good ones out there.
All the domains I sold were found by the purchaser simply typing it into the address bar of a web browser out of curiosity.
With "all of the good ones taken", my better domains are only becoming more valueable and more sought after as time goes on so sitting on them is only good.