WebCron
- Arrange to do tasks at set hours by looking for a page on your website.
- http://www.webcron.org/

Hosted Cron
- This site can help you with the automation that programs need most, a scheduling system that automatically runs the maintenance and cleanup scripts when you need them run, 24 hours a day, 7 days a week, 365 days a year.
- http://hostedcron.com

Change Detection
- Service that notifies visitors about web page changes.
- http://changedetection.com/

ChangeDetect
- Service that saves favorite web pages, monitors content, and sends an automatic email notification when a web page change is detected.
- http://www.changedetect.com/