Timers are valuable when you want to timebox a discussion. I’ve used this planning poker timer when I’m with a team and we are planning our iteration. I also use it when setting 30 minute work goals for myself. It has a nice bell when the time runs to zero, and changes from green to red, giving a nice visual cue.
Mickey Phoenix created this manual planning poker timer which I like even more, if you’re into analogue. kind of a Rube Goldberg contraption with a sand timer and a bicycle bell.