There are so many contributors to the RWD world that it's hard to narrow down a few, but the ones I follow most are:
Ethan Marcotte, the RWD pioneer (http://ethanmarcotte.com)
Luke Wroblewski, the Mobile-first pioneer (http://lukew.com)
Brad Frost, a Mobile-first fanatic (http://bradfrostweb.com)
Harry Roberts, whose well-written CSS articles can be found at http://csswizardry.com
Chris Coyier, who always tackles CSS problems (http://css-tricks.com)
Mark Otto and Jacob Thornton, the Twitter Bootstrap creators (
@mdoand@fat)
As with everything, the best place to find information about RWD is Google, but some sites that often pop up in my search results are www.html5rocks.com and www.alistapart.com.
Also, be sure to get an IRC client and go to the www.freenode.net server and #css channel. Freenode is a gold mine of incredibly helpful gurus, but don't abuse it. It will be obvious if you haven't searched for an answer or if you're trying to get someone to write all the code for you. Be very polite, ask questions, provide a bare bones example of your issue (use jsfiddle.net to create demos), and answer questions once you get better. The more IRC credit you have, the faster you'll get meaningful, educational, and help from it.
StackOverflow is full of questions about responsive design that have already been thoroughly answered, so I suggest you to use Google to do a site search of StackOverflow (for example, site:stackoverflow.com responsive video) for answers to your questions before bothering the nice folks at IRC.
I hope you have learned a lot from this book. You now know the different approaches to RWD and the important gotchas. Go off into the world my pupils! Create beautiful, usable, websites, and get fat stacks!
Feel free to follow me on Twitter at @ccccory—I'm pretty cool, my mom tells me so.