I recently took out a subscription to Copyediting, a bimonthly publication from copyediting.com. The August-September issue arrived by email last week. I wish I’d received it before I’d paid about $200 to upgrade to the Office 2010 suite of programs. Copyeditor reviewed the new release and basically said ‘If you’re already using Word 2007, don’t bother with the upgrade’.
I also signed up for copies of past audio conferences and webinars (much cheaper than signing up to the live versions), and to a training module on sentence structure. I’m currently learning about the difference between transitive, intransitive and copular sentence patterns, which I hope will be useful in explaining my editing decisions to clients.