The R community is one of R's best features (Revolutions)

R is incredible software for statistics and data science. But while the bits and bytes of software are an essential component of its usefulness, software needs a community to be successful. And that's an area where R really shines, as Shannon Ellis explains in this lovely ROpenSci blog post. For software, a thriving community offers developers, expertise, collaborators, writers and documentation, testers, agitators (to keep the community and software on track!), and so much more. Shannon provides links where you can find all of this in the R community:

#rstats hashtag — a responsive, welcoming, and inclusive community of R users to interact with on Twitter
R-Ladies — a world-wide organization focused on promoting gender diversity within the R community, with more than 30 local chapters
Local R meetup groups — a google search may show that there's one in your area! If not, maybe consider starting one! Face-to-face meet-ups for users of all levels are incredibly valuable
Rweekly — an incredible weekly recap of all things R
R-bloggers — an awesome resource to find posts from many different bloggers using R
DataCarpentry and Software Carpentry — a resource of openly available lessons that promote and model reproducible research
Stack Overflow — chances are your R question has already been answered here (with additional resources for people looking for jobs)

I'll add a couple of others as well:

R Conferences — The annual useR! conference is the major community event of the year, but there are many smaller community-led events on various topics.
Github — there's a fantastic community of R developers on Github. There's no directory, but the list of trending R developers is a good place to start.
The R Consortium — proposing or getting involved with an R Consortium project is a great way to get involved with the community

As I've said before, the R community is one of the greatest assets of R, and is an essential component of what makes R useful, easy, and fun to use. And you couldn't find a nicer and more welcoming group of people to be a part of.