Came across this little ditty today, via [Martin Fowler](http://martinfowler.com/bliki/TwoHardThings.html):

> There are only two hard things in Computer Science: cache invalidation and naming things.
>
> -- Phil Karlton

Personally, though, I prefer the corollary:

> There are only two hard things in Computer Science: cache invalidation, naming things, and off-by-one errors.

Too true.