Is HelloHSK! I recently stumbled upon this gem when browsing other Chinese blogs. It’s great because it features preset lessons for each level And divides the material by category, ie reading, writing, etc. I am planning on takin Level 4 or 5 this April, so I can’t attest to effectiveness, but so far this site works great.
The best part is that they have a mobile app. They haven’t updated all the content yet, but when they do, I can see this as a convenient go to for most foreigners.
Here’s the link, let me know what you think – http://www.hellohsk.com