What do you do when some of your members end up copying/ripping your content for their site? I would possibly file a DMCA takedown if the volume of copied material was very large.
Same thing you would do. I'd also contact their host and domain provider as soon as possible. I'd also report them to Google as a spam site.
I'd file a DMCA report too if they never linked the source, and included more then a short paragraph for my content.
I would contact *that person* first, though. Sometimes all it takes is calling someone out for it to get them to stop. It might do the opposite, but then threatening the DMCA reports and whatnot could be sufficient at that point even. If they don't stop, though, then I'd obviously contact people who would take it down.
I tend not to be that bothered as it takes a fair bit of time. My content was first and I will always no that, if they have to stoop to ripping the chances are the project won't last long. I would ask them to remove it and contact the host but that is about my limit.
If it's not their content to begin with (aka they didn't post it or ask permission), I'd contact them and ask them to remove it. And that's probably about it, it's not really worth chasing after people for fairly minor stuff like this.