Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
Timer Tab - Online countdown timer, alarm clock, and stopwatch.
Gnome Clocks - Clock application designed for GNOME 3
Gestimer - For those little reminders during the day
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Online Stopwatch - Online Stopwatch is free to use online tool that allows you to keep track of the important events and tasks that you are performing.