Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
TIMEBOX - An advanced timer for professional meeting facilitators
wnr - Better than pomodoro, this timer app balances work and rest.
MetaClock.com - MetaClock is an Online Alarm Clock that can play YouTube videos and uploaded MP3s as an alarm tune. It supports Chromecast which means you can turn your TV or stereo system into an alarm clock. No installation is needed, it can also work offline.
Date Reminder - Date Reminder reminds you of recurring or nonrecurring events, like birthdays, bills to pay...
KukuKlok - Kukuklok is a free alarm clock available online and offline.