ABLENet page:
http://www.lhup.edu/ablenet/

Primarily for professional adult educators this site provides some
interesting links for tutors (e.g., Literacy Resource Collections; Learn to Use the WWW On-line).

The Educator’s Reference Desk

The Gateway to Educational Materials (GEM)

Ask Eric

Dave's ESL Cafe
http://www.pacificnet.net/~sperling/eslcafe.html

Terrific site!  Great source for lesson ideas.  Be sure to check out
the Idea Cookbook Table of Contents; Idioms; Phrasal Verbs; and
Slang.  There is a lot of other helpful stuff at this site, including quotations, quizzes for students, chat rooms, and links to other ESL sites.

National Clearinghouse for ESL Literacy Education (NCLE)
http://www.cal.org/ncle/

An academic site for ESL teachers which provides ERIC documents (most full-text) about teaching adults ESL.  Provides good background information for ESL techniques and approaches.

Teachers Helping Teachers
http://www.pacificnet.net/~mandel/

Lots of information for teachers with a great section sharing lesson plans. Most of the lesson plans are for classroom use, but can be adapted for small group or one-on-one tutoring