Professor Ted Bunn (no relation), who still gets email about a Black Holes FAQ he wrote over fifteen years ago, recently blogged about what happens when you suspend a Slinky vertically, then let go.

No wait, come back.

In Part the First, he provides an alternate (but equivalent) explanation for the phenomenon.

Allen Downey on his wonderfully-titled blog Probably Overthinking It started in with the equations, which inspired Ted to write Part the Second, which contains with lots of math, but there are also charts.

Okay, fine, I don't blame you for leaving.