To dump a MySQL database:

mysqlhotcopy databasename targetdirectory

To see what the size of multiple directories are without seeing the size of all the files inside:

du -hcs directory1 directory2 directory3

To make an ISO image of a directory to be burned:

mkisofs -R -o newfilename.raw directoryname

To record a CD at 24x:

cdrecord -v speed=24 dev=0,0 filename.raw
  ¶ 10:01 AM