Middle School Talksheets
If I remember correctly, Youth Specialties has been publishing Talksheets since somewhere around the mid 80's. If you are looking for a GREAT way to get your middle schoolers talking about and engaged in your lesson, it's tough to beat Talksheets. The newest edition by Terry Linhart focuses on the life of Jesus.
My Changes and My Future (from the Middle School Survival series)
This six-book series comes to a close with the final two books written by Mark Ostreicher and Scott Rubin. Now that the series is complete, I'm hoping they package them in a cool "box set" parents can give their junior highers.
Group's Emergency Response Handbook
This book is about a year old, but somehow I just stumbled upon it and....WOW! Full of one-page insights into how to minister and respond to issues of grief, divorce, gender identity, addictions and more. On Group's site, it looks like maybe this is only available as a download, but I'm sure there is a way to get hard copy if you'd like. This is a book I would put in the hands of every volunteer in your ministry.