Discord Voice

Settings --> Voice & Video --> Noise Suppression. Set this to "Krisp".

uBlock origin custom filters

||external-preview.redd.it/*.gif?$image
(to block gifs on reddit)

the below are for the stackexchange family of sites
##.vertical-align-content.ot-wo-title.ot-bottom-left.otFloatingRoundedCorner
(some details about why it works))
###credential_picker_container
(hat tip)

SpellCheck

To get a list of all incorrectly spelled words:
cat file.tex | aspell list -t | sort | uniq
(hat tip)

A ffmpeg command

ffmpeg -ss 00:00:00 -to 00:04:12 -i bfbackup.mp3 -c copy output.mp3
This keeps the first 4 minutes and 12 seconds of bfbackup.mp3 and sends it to output.mp3.