I think it's interesting to note that (anecdotally, at least) things that are "less practical" attract far more in-depth SO answers than those that are more "useful in the real world" (insert connection to capitalism) - Haskell/"help me push this into the typesystem" questions tend to attract very well-thought-out answers oftentimes, and usually multiple answers at different levels of abstraction.

(Not that I'm discounting things like the excellent low-level questions on things like cache misses/alignment/"why are sorted lists faster to process", but I think they're rarer.)

If anyone here knows their way around the StackOverflow API and has some time, I think it could lead to an interesting couple of hours.