I've never been banned, but I've done something that could have easily got me banned.
There was a small server I used to play back in late 2010 or early 2011. On this server, you could only mine in some sort of a mine or on a plot that you owned. You couldn't grief other peoples houses and they couldn't grief yours. The server, however, didn't disable TNT damage. Above my house on my plot I decided to build 2 TNT cannons, which I used to launch TNT onto other people's plots. I've even placed TNT on the edges of my plot which damaged neighboring plots.
I have not griefed intentionally ever since.
