[wrycoder]

Waterfall had its place in military and aerospace, where the requirements and API were well-defined, and to a lesser extent in life-critical medical systems development.

But in even those cases, it was largely replaced by Spiral, which is similar to agile and pre-dates it.

Edit: Spiral is like going down the Waterfall two or more times. Similar to agile, but formally documented, with management and customer sign-off up the line, and with a much longer cycle time.