Stealth griefing has to be some of the most fun I've ever had on this game.
Such as venting the stations oxygen supply out. Or causing a major power outage by detaching the solar arrays and jettisoning the fuel tanks for the generator.
Once me and the traitor held up in engineering. We re-routed all the stations power to the engineering room and then used it as a launch pad to cause havoc across the station with space suits. Good times.
I also remember possibly one of the best placed traitor bombs ever. After killing multiple people with normal weapons, the station medics brought them all back to the medbay to clone them. Sure enough the traitor had placed a bomb quite snuggly in a maintenance shaft and detonated it once all/most of the medics were in the medbay with numerous patients and spectators/"gaurds". He wiped out a good 80% of the station population with that one bomb.