Oooh I love threads like this!
For Writers:
EditMinion: For helping you identify editing problems beyond comma placement and periods. Helps with tone, Passive Voice, Weak Words, and all those other goodies!
Query Shark: For those of you looking to be published via agent, this is a great way to check your query letters and make sure they're on point!
Impishidea: This is more other internet denizens critiquing other works. However, in the critique you can see some repeat tropes, overused character moments, and narratives that lose readers. It's a great way to have a lark and also identify in your own work, things that might derail you.
Slushpile Hell: Yet another Query based bit of fun, but it helps to have a laugh and see bad writing when it happens so you can avoid it yourself.
200 Ways to Describe Hair: If there is one thing I notice, it's that when hair is described there seems to be a consensus on a hand full of verbs that everyone uses. This list helps break that up! (And don't you worry, you don't have to use all of them in one novel!)
Grammar Check: Because these are always good to have.
Hemmingway Editor: If you ever have questions about if you work is right for your target audience, this editor can help! It assess you word use and sentence complexity to tell you what grade the book is best for. (This is very helpful in the case of YA or Middle-grade)
For Artists:
ArtRage: Essentially it's a tutorial hub and you can look for whatever you want to here, whether it be backgrounds or characters.
Figure Drawing Lessons: A youtube series about figure drawing that can be very helpful. (I started with the second video in the series, because the first is more introduction rather than right to the lessons.)
Design TutsPlus: A tutorial hub that deals with drawing animals of all kinds!
How To Draw a Background: A video that gives some great tips on background creation that can be applicable to a lot of different backgounds.
Color Matters: Info about color theory and why it's so important!
Light and Shadows: Important info about shading and shade values!
Still Life Tutorial: A still life drawing lesson (which is useful for creating objects in a scene).
Hope these resources help! Cheers!