My favorite (not listed) remains the Hard Drive maker who published an announcement of the WOM (Write-Only-Memory) into which you could put an unlimited amount of data in any format you wished. It was a full page ad in several Techie magazines, and elicited a "few thousand" serious requests for additional information.

One company spokesman commented that the only ones who got mad when they found out it was a joke were the ones who really wanted one.

The accompanying photo appeared to be a short piece of 2 x 4 lumber, painted black, with a serial cable nailed to one end.

Hardly anyone seemed concerned that you could not Read anything back. It appears to persist as the device invisioned by those who write all of Microsoft's backup programs and the instructions for how to use them.

ca. early 1980s IIRC.(?)

John