hammy

This library provides programmable, interactive interval timers for
Emacs.  They can be used, e.g. to alternate between working and
resting periods, to remind yourself to stretch your legs, etc.
Timers, called "hammys," are easily defined by the user to behave
as desired, and they can be integrated into other programs by
calling Lisp functions in the hammys' definitions.

FAQ

Q: Why are timers called hammys?  Isn't that silly?

A: Probably, but is it sillier than calling them tomatoes?
Besides, it helps to distinguish them from Emacs's timers, which
are used in the implementation.