As a sysadmin in the 90's it was considered malpractice to not have a copy of tomsrtbt[1] available at all times. The idea was, in a pinch, if you brick your internet gateway you'd have a chance of recovery by booting from tomsrtbt. It had just enough tools crammed onto the disk to fix configurations, fsck a disk, and rewrite the bootloader.
Only one of five mirrors works, but then I discovered that the last version is from 2002, so I guess it's surprising that Ibiblio still holds out.
I vaguely remember the name—however from some time recovery tools changed to mini-CD for me, which is not too large either with ~170 mb or something like that. I gotta find the name of whatever recovery-CD build I had, since it's got memtest86+, which can still come in handy…
Hiren's? It's got a pretty ancient version of Memtest86+ on it these days FWIW. Then again for some hardware I touch the newer memtests and Darik's don't boot.
There was a cottage industry of interesting floppy distributions back in the day. I remember Hal91 (mostly for the ascii art and the creator's email at an online.no domain - funny for a young student who hadn't internalised the meaning of ccTLDs) and muLinux (which used superformatted floppies to cram an amazing amount of stuff into those few megabytes).
I used to use tomsrtbt as a daily driver in an old 486 that I removed all the moving parts from. A totally silent machine, after reading the OS into memory from the floppy.
[1] http://www.toms.net/rb/