Running Glider was one of the most entertaining things I did while playing. Glider comes with default behavior for every class, but you can develop your own in C#. I ended up writing some code for my druid to be a "Healbot", basically causing my character to run around and heal nearby allies.
It was quite simple - it would search for nearby players and try to stay in the middle of everyone. It would throw heals over time on anyone within range that was slightly injured, and cast big heals on people taking a lot of damage. I used it to farm honor in the PVP battlegrounds. After letting it run for hours, I'd take a look at the chat log and see lots of tells from people thanking me (it) for heals. Never once saw a comment calling it out as a bot. The mod I used to queue battlegrounds took screenshots of the match results, and many times my bot was #1 on healing (often by a large margin).
It was fun tweaking all the settings, by the time I maxed out on honor the code was pretty robust. I ended up modifying it a bit to follow around specific people (awesome for power leveling).