Out of Office Email Generator - Personalized, witty OOO replies for guilt-free vacationing.
FollowUpThen - The simplest way to schedule an email reminder
Rebump - Automatic follow up emails. Keeps on bumping until you get a reply.
Right Inbox - Schedule Emails in Gmail To Be Sent Later
Excuse generator - Don't want to go to office? They are here to help.
LetterMeLater.com - LetterMeLater.com allows you to send emails to anyone, with the ability to have them sent at any future date and time you choose.