If you're running a modern Linux desktop, you should have a "notify-send" command which will cause a message to be displayed by your desktop-environment's pop-up notification system (on Ubuntu, this command is in the libnotify-bin package). I have two scripts I keep around which I call "notify-success" and "notify-failure":
notify-success:
notify-send --icon=gtk-dialog-info Success! "$*"
notify-failure: notify-send --icon=gtk-dialog-warning Failure! "$*"
When I want to run a long-running command and don't want to have to keep checking on it, I'll do something like this: make -j3 && notify-success "Build complete" || notify-failure "Build failed"