I've been noticing that periodically my MySQL service will hang and require a restart. It's easy enough to SSH in and restart it, but I only catch it after the fact. So I wrote this little script which curls my website, sees that it's down and restarts MySQL and shoots me an email with sSMTP. This only checks for the MySQL service not accepting connections from Apache. If there's an error with Apache, or it's not running this won't do anything.
tl;dr

#!/bin/bash  
  
#Downloads index to specified file, use wget if you don't care what it's named.  
curl --silent -o /scripts/temp/index.txt https://robbiecrash.me -k  
  
#Silently diff the downloaded file with a copy of Apache's default 'can't   
#connect to database' html page and execute actions if they match  
if diff /scripts/temp/index.txt /scripts/___NoDB.txt -q > /dev/null  
        then  
                # Restarting would bung up the script if it wasn't running  
                /usr/sbin/service mysql start  
                # restart incase it was already running but hung  
                /usr/sbin/service mysql restart  
                # Add the date to a log file  
                date >> /var/log/sqlService.log  
                # Create and mail temporary copy of the message with date  
                cat /scripts/checkSQL.msg > /scripts/temp/checkSQL.msg  
                date >> /scripts/temp/checkSQL.msg  
                /usr/sbin/ssmtp MYEEMAILADDRESS < /scripts/temp/checkSQL.msg  
fi  
  
rm /scripts/temp/index.txt  
rm /scripts/temp/checkSQL.msg

The file checkSQL.msg is just a normal ssmtp message file like so:

To: MYEEMAILADDRESS  
From: MYEEMAILADDRESS  
Subject: Database unreachable  
  
The database failed a connection attempt and the  
mysql service was automatically restarted on: