English Grammar: Anything having to do with grammar and writing.  Very useful and informative!  http://www.englishgrammar.org/

 

The Purdue Online Writing Lab: Famous writing site that boasts over 200 free resources!  https://owl.english.purdue.edu/

 

My English Writing: Great site to see other ESL students' writing samples.  Nice site that can show you corrected and uncorrected formats of many essays.  http://www.my-english-writing.com/