Thanks for all your help. I now have a nice backup script running. What I'm planning to do a little later this summer is to set up a RAID backup server on my DSL connection ftp downloading the mysql databases every night from my co-location server. This way I will have a nice archive of dumps on two locations to be even safer.
In my setup I now have 3 my.sh scripts executed at the same time through a cronjob. Could it be problematic to do this at the same time or does it not matter? The databases aren't large. Cheers, Andreas