Root-tail displays a given file anywhere on your X11 root window, i.e. it is
kind of tail -f for multiple files using your desktop background as output
window.

It has configurable colors, fonts, wrapping, justifying, continuation
indicators, geometry, and more and can interleave multiple files also making
it a sort of multi-tail.

For example: 
root-tail -g 800x250+100+50 -font 10x20 /var/log/messages,green \
  -font 12x24 /var/log/secure,red,'ALERT'