The Able Writer: A Rhetoric and Handbook

 Grammar and Style Notes by Jack Lynch (University of Pennsylvania)
 
 Guide to Grammar and Writing (Capital Community-Technical College) 

 Ask Miss Grammar
 
  On-line Technical Writing Textbook (accompanies on-line text): Austin Community College

 Elements of Style by William Strunk, Jr. (classic 1918 version)

  MLA Format and Citation Guide

  OneLook Dictionaries (215 dictionaries)

 A Web of On-line Dictionaries (more than 400 dictionaries)