Resources I find valuable

Online Etymology Dictionary

Purdue's Writing Lab called OWL is the most amazing website I've seen yet.

Just a few of the resources they make available:

Writing on and With the Internet

Writing Across Curriculum

ESL Resources for Teachers

Internet Resources for Teachers

Online Resources

And as a Graduate Student my personal favorites:

Genres of Writing

Academic Cover Letters

Writing the Personal Statement

Resumes

Writing the CV (Curriculum Vitae)

MHRA
(Modern Humanities Research Association)

Oxford Journals