I've had a go at writing a tar.bz2 to a dvd+rw
tar -jc /home /etc | growisofs -Z /dev/dvd -stream-media-size <something too large>
That gives an error with the media size, which I then typed in. That reported that the burn had succeeded. Looking at /dev/dvd with 'less -f' shows an iso file system with a tar in it. I think I need to put mkisofs in the middle or pass some more options, but I'm not sure. Regardless, it hasn't worked as I'd like as neither 'cat /dev/dvd | tar -jt' or 'mount /dev/dvd /dvd' work. The latter gives the error 'mount: Not a directory'