Peer editing would also be a great way to spend time. I work with my classes on specific skills, and review rubrics with them prior to assignments. With direction in what to look for and in constructive criticism, kids can be very valuable as "assistant teachers" with other kids. I tell them to start out commenting on what they like, then look at specific skills (i.e. use of imagery, use of action verbs, etc.) and make suggestions as to improvements. The writer then makes revisions for a better end product. The best part is that kids learn to recognize mistakes in their own writing by taking a critical view of others', and their writing inevitably improves as well.
I'm sponsoring a book club for my junior high school this year. Some of the ideas we are considering are:
Hope this helps and good luck!