Lessons from Nothing: Activities for Language Teaching with Limited Time and Resources is a great book for teachers short on time and with little or no resources.
There are over 70 activities in the text. The majority are fun word games that focus on improving grammar and vocabulary. The most they require is that the students have a paper and pen, but many activities require no resources at all, not even photocopying! The exercises can be tailored to all levels but are generally more appropriate for lower levels. It’s a great book if you’re going to teach in Asia with large classes and minimum resources.