Not to sound like one of those people, but a bidet. It hasn’t eliminated my use of toilet paper, but certainly has reduced it, while leaving a squeaky clean feeling. I miss using it while away from home nowadays.

Other things are eye masks (I have sleep quality issues) and ereaders (never moving with ten boxes of books again).

Some recollections from Reddit:

A bot that links the top posts of all time for a community. Gives a good sense of the community’s greatest hits when referenced in discussions.

A bot that converts imperial to metric units or vice versa. Some people do find this one annoying, but as a metric user, this one helps me understand miles and pounds, etc.

A bot that summarises or pulls the first paragraph of a Wikipedia article.