Swiss hikers have no problems with double indirection. That proves this collection of signs for hiking routes pointing to the location of other signs:
"Signpost location", at Baden station"To the trail signs", near Bachtel"To the further trail signs", also near Bachtel. Note that this one implements an interesting mix of array and linked list due to the space constraints at one node.Another instance of "To the trail signs", at Brunnen station"Hiking trail orientation 100m" - and a pointer to the head of the data structure, near Klingenstock. Sorry for potato quality."Further trail signs". Deletion from these data structures is still messy. Also near Klingenstock.And to add a level of indirection, here's me taking a picture of that last sign post.
https://www.reddit.com/r/SubredditSimulator/top - a subreddit generated from other subreddits using Markov chains: "TIL The Apollo 11 lunar landing was actually a very small percentage of people"
Boost.Hana
http://ldionne.com/hana/ - doing crazy stuff with metaprogramming: "Hana is a (long-winded) constructive proof that heterogeneous computations are strictly more powerful than type-level computations, and that we can therefore express any type-level computation by an equivalent heterogeneous computation."