n98-magerun – the Swiss Army Knife for Magento
by netz98
Command line tool. Updates admin passwords and creates admin users, shows conflicting class overrides, and dozens of other useful functions. Indispensable for Magento development.
https://github.com/netz98/n98-magerun
Admin Login Log
by siliconrockstar
Creates a sortable, filterable log of all the logins to the Magento admin area.
https://github.com/siliconrockstar/magento-admin-login-log
ShowConfig
by siliconrockstar
Add a url parameter, get a dump of the global config object.
https://github.com/siliconrockstar/showconfig
Discomage
by siliconrockstar
Magento server discovery shell script. Useful for when you just logged into a server you know nothing about.
https://github.com/siliconrockstar/discomage
Uptime Robot – Free website monitoring
I’m not an affiliate or anything, I just really appreciate this site. I think it allows you to set up 50 alerts for free.