I love using Fastmail's Snooze feature.
I often use it to make sure that I always have any time-sensitive event tickets or travel details visible on the exact day and time I need them to be.
Instead of digging through my email to find a theatre ticket I purchased three months ago, I snooze the email as soon as I receive it to the morning of the event day, so it always pops up right when I need it.
-Rasha, Fastmail Plumbing, US