Chin-ups and Pull-ups separate the men from the boys (or women from the girls).  Most people stay away from the bar.  It is much easier to play with a nautilus machine.  Chin-ups and Pull-ups are an excellent exercise to work the back and biceps and you can add variety by changing from a narrow grip, to a wide grip, as well as many different techniques mainly dealing with your grip.

As you can see, the bar I have below also has my blast straps and ab slings hanging from them.  Combine a chin-up bar with these 2 additions and you can work your chest, shoulders, triceps, back, biceps and abs all on this very inexpensive gym.  Of course... this works much better if you have exposed joists in an unfinished portion of your basement.  You can also see a steel ring around the pipe next to my straps... this allows me to clip my stirrup handles to the bar with cable clips for yet another different grip.  Bottom line is, you can do your chin-ups and pull-ups with just the bar bolted to the ceiling with the pipe straps and lag bolts.

The setup I have here uses a 36" x 1 1/4" black nipple pipe (threaded) with the appropriate end caps.  The end caps both finish the ends of the pipe, as well as prevent any straps from slipping off the end.  I've also recently added a few 120 degree elbows, along with 5" extensions to allow for wide grip chin-up work.  I used standard pipe straps with 1 1/2" lag bolts to fasten the pipe to the ceiling.  I put 2 straps per side just to be sure. 

The above configuration is actually my preferred chin-up bar setup, even though it's not a bar.  I screwed 2 nice sized eye hooks into the floor joists of my basement and attached a heavy duty spring clip to each.  Although I typically use my stirrup handles (on the right) for my chin/pull work, you can easily make a set of handles with some PVC pipe and rope (on the left).  I really like this low cost alternative since it allows more natural wrist movement.  The spring clips also make it very easy to attach my suspension straps, ab straps, close-grip row handle, towels, etc... for a variety of options in a small space.

These are very simple equipment alternatives that can provide you a great deal of benefit!  If you don't have the tools or space to put a chin-up bar... find the closest playground or tree branch to get the job done!