root-tail is a graphical version of the UNIX tail command. A real-time tail output (of any file you choose) is sent to your desktop. Your desktop will show the last few lines and any new entries that are added to the file you specify as they are added.
If you'd like to monitor your /var/log/messages file in real-time (with a nice, ugly green color ;) and left-justified), you can install root-tail, and run the command:
root-tail -color green -g 80x50+0+100 -shade /var/log/messages &
Here's another, from root-tail --help:
root-tail -g 80x25+100+50 -font fixed /var/log/messages,green /var/log/secure,red,'ALERT'