CUBING SITES:

Official WCA webpage- It's got all the records, rules, everything official about cubing.
Ruwix- Named the official Rubiks website. Has loads of stuff such as simulators, timers, and even humor.
Cube Depot- Cool site where you can buy cubes, most of the time it's pretty cheap. These guys are as trustworthy as Amazon.
Amazon.com- If you've never been to amazon, it's a great place to buy cubes. They are generally cheaper, but check elsewhere, especially cube depot.
Cube Timer- Best online timer for cubing.
Cube Smith- Buy parts and pieces for your broken cubes. Mainly focuses on the larger cubes, and does not supply odd shaped ones.
BadMePhistos- Excellent Fridrich's Method teacher.
Cube Notation guide- This is on ruwix, and is excellent if you're a little rusty on notation.
Rubiks.com- The official Rubiks website, has a store, history page, you name it.

CUBING YOUTUBERS:

The RedKB- Lots of unboxings, reviews, and tutorials. One of, if not the, best cubetubers
Tony Fisher- TONS of new cubes.
Feliks Zemdegs- Fastest cuber in the world, willing to make tutorials. Definetely check him out
Collin Burns- Fastest single in the world, obviously has some good stuff
Mats Valk- One of the fastest cubers in the world, has some great stuff on his channel
The SergsB- Mainly focuses on tutorials, some of his older videos are cool.
MeMyselfAndPie- Very human fellow. He's a good person with a good chanel.
Paradox Cubing- Very good teacher for learning new methods