For Teens
Websites
Grammar Girl — answers grammar and punctuation questions
NaNoWriMo Young Writers Program — write a novel in one month and set your own word count goals
The Make It Safe Project Writing Scholarship - an annual writing scholarship and publication opportunity for queer and trans teens ages 13-18
Scholastic Art & Writing Awards — a national art and writing competition for teens in grades 7-12
TeenInk — a writing magazine for teens ages 13-18
Young Writers Society — online writing community for teens ages 13+