Monit is a linux software that allows you to monitor your linux machine (services, processes, disk partitions, network connectivity and more). More important, it is absolutelly FREE!
It has a built-in system to restart your linux services (assuming you monitor your httpd server, monit will check periodically if the httpd service is running. If not, it tries to restart it and you also get a notification (no matter if the restart was susccessfull or not)).
It is compact, modern, easy to install and customize and uses really small amounts of RAM memory (around 15-25 MB). It also has support for MySQL databases. It has a built in http server (in order to manage monitor over the web). You can access monit in your web browser, either using a regular http:// connection or you can generate a self-signed SSL certificate and access monit using https:// over an encrypted connection.
For a full list of features you can visit monit official website.