Teacher Discussion Forums

I'm writing a Teacher Resource Book to accompany a Student's Book. I want to make this a useful tool for teachers and not just added "stuff" to overwhelm a teacher. If you were to have the ideal Teacher Resource Book, what would it include? Activities? Handouts? Photocopiables?
Any ideas are much appreciated.

Here are some ideas -

warm-ups - short simple fun activities to introduce the topic of each unit

extra communicative activities - photocopiable worksheets that will generate speaking practice for the target language or topic area. At beginning to pre- intermediate level short information gap activities giving lots of practice of a structure would be useful

worksheets/lesson plans for listening tasks - I often find I exploit the listenings in textbooks in a different way to the way the textbook envisages.

lesson plans - alternative or supplementary activities to overcome textbook deficiencies - all textbooks have some parts that don't work - perhaps because they do not relate to your students need or level. Create your own activities to bridge the gaps

songs - find some songs that relate to the target language or topics in the student books create a task that focuses on the appropriate vocabulary or grammar.

The key point I think is that activities should relate specifically to unit themes in the student book and not just be random good ideas. They should help engage students in the textbook material, give further practice of target language or topic based discussion, assist teachers exploit textbook material or replace unsuitable tasks.