D&D 5th Edition Homebrew Resources
The new edition of D&D has inspired a large number of people to "roll their own," and with modern desktop publishing tools being available so cheaply (or even free), it should come as no surprise that a lot of it is really polished. Here are a few sites that I find particularly useful; I can't swear to the balance of all of their materials, but there are some great ideas in there and some very polished game elements I use myself.