I remember joining some clan run fort dm server. It was in build box, and the forts were built in the upper area where the four baseplates were. I didn't realize it at the time, but the clan was using modified shotguns and crouching through bricks to hit everyone in the server, without even giving them a chance. Of course, being new, rather then leaving and finding some other server, I just stayed in the server and asked them to stop. Which didn't really result in anything.
I played a few missions on Isles of Blockland, and helped build a giant cherry pie.
For a while, I used to play on BlueDragon's server, because of the interesting environment it had. Usually, the map consisted of a giant lake of lava with some really wierd texture stuck on it, and a bunch of baseplates floating in the air above it. I think it must have been kitchen without the kitchen interior, and a bunch of lava. Anyway, I'd build all kinds of stuff on that server.
I also remember Uso Da Namu building tons of spawn traps. The last time I had seen him, he built that interior based one filled with weapons, and watched people DM inside a very tiny space. That might have been Piccolo though, and I'm just remembering it incorrectly.
Also, there was Skizot's mod and The Scenerio Mod (BJ_Way's mod), Fort Mod, and RPG Mod (I think Plague made that one, it could have been Pelouze though), which were rarely even played.