Free ESL worksheets

Since February, I've been teaching Adult ESL courses.  Its been quite an incredible experience teaching adults instead of children.  I am still learning what approaches translate and which ones do not have the same effect with adults as they do with kids. Some of my findings thus far:

• Games and candy make both adults and children happy
• Competition goes a long way in building memory
• Repetition, but in different ways makes a difference (this is where games come in)
• Reviewing things learned from previous class at the beginning of the class builds confidence for students and the teacher

I use a curriculum, but sometimes it isn't enough to drill a point home.  In search of quality free printable worksheets, I'd like to share my top 3:

Sticky Ball - free printable worksheets that progress from concept introduction to application

ESL Tower - large collection of free printable worksheets, wide variety of topics

The Language Guide - great vocabulary resource, includes audio so parents can listen at home to practice pronunciation

Are you an ESL instructor? What resources do you find most helpful? I would love to read what you are using.