Early in the game's history, there was a particularly naughty nasty trick you could play on people that involved runes and Moongates. It was incredibly annoying yet hilarious. GM's (And the victims) absolutely hated people like us for pulling it.
We had coded runes in our guild, and Whenever anyone in our guild had a rune marked "Home" or "Guild" or "Britain", it was bad news for whoever picked the thing up and used it. Those runes always lead to tiny islands we found while out on the ocean in a boat. We would often walk around Britain, stealing people's runes, and making sure they ended up with those runes, while one of us waited on the Island. Or, we would just open a gate by the Brit Bank and see who decided to jump in. Once there, we would kill the person, loot them, and leave the ghost completely stranded on that tiny island until a GM came and got them off. It became such a widespread problem that Gm's eventually had to install teleporters on some of the smaller islands and prevented access to others. It was glorious.
And who could forget the runes that instead lead to the most dangerous parts of dungeons like despise, or isolated "lairs" where people had untamed dragons waiting to kill whoever entered so they could return for the loot later.
"Logjam Boating" was a form of Griefing that a specific alliance of guilds implemented. Some guilds early on stole dozen of boats. Literally. The guilds worked out a plan together to park their stolen boats on every possible landing spot in Buccaneer's den, and then locked them down and left them there to prevent all other boats from landing. The guilds went on a mass Dreadlord killing spree, and owned the Island for a brief time until a few other guilds who had Runes marked for the Island, gated in all at once in a large PVP battle.
Carpentry Griefing was one everyone remembers well. One minute, you are not paying attention, and then next, someone has built a table and piano around your character, trapping you in the corner:)