For backing up our mysql databases we are using a script which is avialiable under GPL License here:
http://www.cyberciti.biz/nixcraft/vivek/blogger/2005/01/mysql-backup-script.html
(Note that we are not responsible for the content presented on cyberciti.biz)

We modified the script for our purpose:
- simple check, if the dumpfile is complete
- simple logfile for each backup process
- general logfile with little statistics (csv format)