fcron - Fcron is a scheduler designed for Unix/Linux systems, especially usefull when your system is not up all the day long.
Simply Remind Me - Free email and text reminder service so you don't forget the important things in life!
Anacron - Anacron is a periodic command scheduler. It executes commands at intervals specified in days.
FollowUpThen - The simplest way to schedule an email reminder
mcron - mcron is GNU's implementation of cron. It is a 100% compatible replacement for Vixie cron.
Auto Mail Sender - Auto Mail Sender Standard Edition official page. A powerful and easy-to-use eMail scheduler.