This page contains information intended to be useful for Flight Instructors or Flight Instructor candidates. However, there's no reason it won't be useful to all pilots.
Make sure to check-out the Student Pilot pages, you may find material there you can use with your Students.
To study for the Flight Instructor oral, or in practicing your profession as a Flight Instructor you're going to need some reference material.
Logging Pilot Time - for CFI's and their clients on logging pilot time.
CFI checklists - a discussion of the memory checklist CFI's might want to use.
Pairing up for IFR training - an article intended for instrument students looking to share time with another pilot as part of their instrument training.
Global Positioning System - various articles and reference documents.
Endorsement Records (Excel)
Syllabuses
A curriculum and syllabus for CFI training:
Ground School Lesson Outlines for use when you can't fly.
Lesson Planning
Ground School Teaching Notes.
Other miscellaneous documents:
Learning to Use Your GPS - discussion on what features of your GPS you need to learn.
Emergency Procedures - the ABCDE approach.
Teaching the NDB/ADF - notes from George Scheer.
Teaching weather briefings - 8 "slides" in WORD format.
Here are some sites with CFI lesson plans on line. I STRONGLY recommend that you sit down and write your own lesson plans. The main purpose of that is if you organize them and write them down you'll know the material. If you just print out somebody else's lesson plan, well you'll have lesson plans, but will you know the material? Anyway - having other people's lesson plans to look at is still useful, so here they are:
Here are some other really useful CFI links.
This is a list of questions and answers from Rod Machado that were originally published in AOPA's Flight Training magazine.
Some useful other Internet sites for Flight Instructors.

If you're a CFI, consider joining the National Association of Flight Instructors.
You should definitely consider being a member of AOPA.