[brk]

Cuecat? Though I'm not sure if that ever really got big enough to warrant a spot, but it was a thing for a hot minute.

HomeRF - The wifi contender that was supposed to unify wireless networks across multiple device types.

Tivo - technically still around, but pretty much a zombie version of their former selves. (Maybe make an "I'm not dead yet!" section).

Gateway 2000 PCs -Their support line had a DJ, and they were everywhere until all of a sudden they were nowhere.

Optical Drives

Zip Drives - 100MB on a floppy! OMFG!!!11

Slashdot - Digg and Reddit's funky uncle.

[zorked]

Interesting Cuecat story: LibraryThing bought a massive stock of Cuecats and, 20 years later, they still sell them, repurposed to scan ISBNs from books for cataloging purposes: https://wiki.librarything.com/index.php/CueCat_Guide

[cestith]

Slashdot is still online and updating. Some of us still use optical drives from time to time (especially those of us with an existing stock of M-Disc media for long-term archiving).

Gateway was purchased by Acer, so it’s not like they just disappeared. Not any more than DEC, SBC, or Studebaker anyway. They were just absorbed.