http://college.hmco.com/devenglish/students/dev_writing.html
Companion site for the Grammar to Go textbook for ENC 0002

http://grammar.ccc.commnet.edu/grammar/ 
Use as a reference or writing site . . . includes quizzes!
Everything you need is right here.

http://owl.english.purdue.edu
Online Writing Lab (Purdue University).  Sources provide writing help, links to other writing labs, excellent examples, and Internet links for various subjects.

http://www.chompchomp.com
Rules, handouts, and interactive quizzes-- Try this!

Reference Sites:

http://www.google.com/
One of the largest and oldest search engines

www.dogpile.com
Another great search engine--lots of sites, quickly!

http://www.ask.com
A cyberspace butler who answers your questions and directs you to internet sites

http://www.infoplease.com
Got a question?  This site has the answer.

Vocabulary/Spelling:

http://www.wordsmith.org/awad/index.html
 Learn a new word every day by visiting this site or subscribing.

http://www.facstaff.bucknell.edu/rbeard/diction.html
Over 100 on-line dictionaries--everything you need

http://www.thesaurus.com
Offers access to dictionary, thesaurus, and reference links -- very useful!
 

Essay Writing:

http://members.tripod.com/~lklivingston/essay/
Nice guide with essay writing tips and example essays 
Be sure to visit this one!