Once in a while I do a quick search on resources for copy editors. I'm usually looking for workshops or conferences in my area. I enjoy meeting other people in my field -- it's energizing and fun to talk to others who do what I do.
Here are a few of the professional organizations I found:
The Editorial Freelancers Association (EFA) -- is for editors, proofreaders, writers, proofreaders, researchers, etc. and has been around since the 1970s. It is a resource for freelancers and for those looking for freelancers. One of the best things I've found on their site is their editorial rates chart. So helpful!
Copyediting.com -- offers helpful articles about editing and training for professions. You can also sign up for their newsletter. Very informative!
American Copy Editors Society (ACES) -- holds bootcamps for copy editors and an annual conference. It's at their annual conference that many AP and CMOS changes are announced. One of the more recent being no longer capitalizing 'web' or 'internet.' Cool stuff!
These are just a few I frequent...are there sites you have found that have helped you? Please share!