Eusing Clock - A beautiful and fully customizable alarm clock.
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Gnome Clocks - Clock application designed for GNOME 3
T-Clock Redux - T-Clock Redux in an enhanced fork of Stoic Joker's T-Clock 2010 with ISO week number support...
Digital Clock 4 - Beautiful customizable clock with plugins