very useful for multi-time-zoned projects. Working with overseas times means you get good at mental translation but with daylight savings, people moving around, new people on the project, etc - it becomes very handy.

One of my favorite clock related features is in KMail where it says "Senders current time", which is often helpful as well.

It was added because I have co-workers in five different timezones and servers that use UTC. It's handy to have that info at a glance.

IT projects be it open source or closed source often span the US, Asia and Europe.

After a while you memorize the time zone differences. But to be sure and take daylight savings in account world clocks are not bad.

I use a world clock every single day.