Favorite obsolete formats.....

Sony Beta Max used for audio only. Phil Collins used these to mix Face Value.

You guys beat me to the punch with Elcaset.  I do remember listening to a really fabulous system (1980ish?) that had an Elcaset, it was actually excellent for the time. If memory serves it ran at double cassette speed, which would have been 3.25 ips.
Can't say I miss it, but it really knocked me back at the time.

Regards,
barts

Aside from the clumsy storage size; I miss Laser Disks. Mostly because after inserting them; they would just play. Minimal amount of superfluous warnings and ads. It’s frustrating when playing children’s DVD’s to have keep pressing buttons or be subjected to endless advertisements, year after year, for discs you’ve already purchased. It was also nice to be able to read librettos and linear notes without eye strain.

dizbuster. Wow! Very interesting. Thank you for sharing that. 

Cassettes with great SQ and recording on a top quality deck never ceases to amaze.