Simple Alarm Clock - Simple open source alarm application for Android devices.
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
Alarm Clock Pro - iTunes alarm clock, stop watch, timer, and more!
Gnome Clocks - Clock application designed for GNOME 3
KTimer - KTimer is a little tool to execute programs after some time.
Digital Clock 4 - Beautiful customizable clock with plugins