I find it fun trying to survive in a griefed environment in Minecraft, but it is tedious to create a new map, build lots of large buildings, half-tear them down, and then build thousands of tall towers out of random materials. Is there a world generator that can create griefed maps like this automatically?
No, there is no known map generator that will create a griefed style map. It's not impossible, but would require a very large effort to create the generator.
I would suggest going to the Minecraft forums and making a Request in the modding section. When you make your post, try to write out possible specifics for the generator.
Hopefully a modder will come along who's interested in helping. Things can then move forward from there. If there's no response there, try over at the Bukkit forums.
Hope this helps.
Perhaps taking alot of premade maps and let people come onto your server in perhaps using the Nodus IRC, i had setup a Griefing server and bunch of people came and of course, griefed it all! Was pretty fun and some people donated for WE.