If you work with people across multiple timezones, it's really useful to be able to open a screen with a set of clocks and glance at the time in every relevant timezone.

If I just have https://time.fyi/timezones bookmarked, it seems to remember the timezones that are important to me. Definitely convenient and far easier than doing multiple searches or using a phone's multiple clocks(?).

This site is useful enough and it's a nice execution.