There are two great resources I found recently and I am going though them as we speak.
The first one is a course on Statistical Learning, which can be accessed here.
The second one is a course on visualization by using the ggvis package in R, which can be found here.
Another great resource I would recommend is the R-bloggers site, which consolidates a lot of information about the R community.
If you have ideas about other useful resources, drop me a line.