Another piece of equipment that I like to use in my home gym is an abdominal roller. I alternate ab exercises and use the ab roller about once a week or so. It takes a little getting used to but if you use it correctly, it will work your abdominal muscles. Ab rollers are inexpensive and take up almost no space in my home gym. Try one out and let me know what you think.
The ab roller is a nice addition to your home gym and it takes up almost no space.