A site dedicated to small kata's and hack's to be used as short, sharp, sample coding exercises. These are the types of things candidates are typically asked to do as pairing exercises, or as remote interview exercises, but can equally well be used for group codebar or code club exercises.
Typical format is to have the master branch contain the problem description and no code. There are then branches for just tests (in a given language) and addtional branches from this to include different implementations of solutions. This should give the user the freedom to look at exercises, without accidentally being exposed to the solution from the off.
So, many of the exercises come from either recruitment or teaching experience. Also, several resources and ideas are reused from this excellent blog post. At some point maybe the exercises should be rated for difficulty/time required, but that's to come.