SendRecurring - SendRecurring allows you to setup, send, and maintain scheduled email reminders.

Callpage - Turn website visitors into sales calls. Use CallPage and provide immediate free phone callback to your leads in 28 seconds.

Recurrr - Send recurring emails

Novocall - Novocall converts web visitors into sales calls in seconds.

Followup.cc - FollowUp for email is a lightweight productivity suite that keeps your conversations and tasks from slipping through the cracks. Set perfectly timed reminders that arrive at the top of your inbox, right when you need them.

Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.