Simple script witch help you can backup /home/<username>/projects folder. It's usefull than all users have the same directory in their home dir. It also makes backup of all databases by copying database files and archiving them.

Script code. It automaticly deletes older files than 7 days.

#!/bin/sh
echo Backup Started `date`
# Paths
baseDirBackup=/backups/sites_backups
targetDir=/home/www

users=$(find /home/ -maxdepth 1 -mindepth 1 -type d)

for homeDir in $users
do
if [ -d "$homeDir/projects" ];
then
   echo "Creating backup for $homeDir"
   dirBackup=$baseDirBackup/`date +%Y%m%d`/${homeDir/\/home\//}
   mkdir -p $dirBackup;
   tar czfv $dirBackup/sites.tgz $homeDir/projects
fi
done

mkdir -p $baseDirBackup/`date +%Y%m%d`/databases
tar czfv $baseDirBackup/`date +%Y%m%d`/databases/databases.tgz /var/lib/mysql

find $baseDirBackup -mtime +7 -delete
echo Backup Completed `date`