My old team (442) built an arm that was 30' long in 2002. They used it to reach over all the other bots and goals and back to the home zone area. It used strings/pulleys/cables whatever. I'm not sure what kind of string material they used, but I know pulleys were involved.
Although I never really approved of building it, the few times it worked were kind of impressive. That is, until the top snapped off, swung by the string, and almost killed a referee. But, eh, it's all the same.
