I leverage Marketo, HubSpot's blog, Pedowitz, SEOMoz, and many of the demand gen agencies' blogs to increase skills and keep up with innovative ideas.
The LinkedIn Groups are a good idea. I wrote a post about this if you check out
The Sirius Decisions blog is excellent..
Agree on what Elliot & Josh have posted. Also check out the following, which will be enough to keep you busy for a while:
Associations (websites & LinkedIn Groups):
Marketing Automation Institute (MAI)
Sales Lead Marketing Association (SLMA)
American Association of Inside Sales Profesionals (AA-ISP)
Business Marketing Association (BMA)
Marketing Executives Networking Broup (MENG)
Content Marketing Institute (CMI)
American Marketing Association
BtoB (full disclosure - this is published by a division of our company)
Chief Content Officer
Blogs (not listed above)--search on company website or use your favorite search engine
Orbit Media (http://www.orbitmedia.com/blog) & book Content Chemistry
Heinz on Marketing
I'm sure I left some out, but this will be enough to get you started.
I'm willing to see if more people post stuff. :)
My US management is also a big fan of Sirius decisions and this is indeed a good source of info, especially to know the industry standards (even if in real-life it's often quite different!).
There is a wealth of information out there that I wasn't aware of. I've heard of some of the resources listed but not all of them. This will definitely keep me busy for a while.
I appreciate all the answers so keep them coming!