Let me just clarify this, @
Ohorichard and @
42trojan42. A server administrator would not trust any plugin that is not verified by a trusted source. Installing the .jar file could be a possible way to edit the ops.txt file. Again, the plugin has to be verified by a trusted source. Only a dumb owner with no clue on how to do things would install that jar. I'm actually thinking about making a .jar file that would change the ops.txt.
Edit: I just realized... I don't know how.