The bar dip/pullup "assist" machines at the Gym are great. I went and
attempted to make one out of common items, basically three 2x4s and
some hardware. Check it out. Only cost $40.00 to build. Bar dips are
great especially if you can do some then do some more with assistance
until you get a good upper body workout.
airspring assist bar dip
http://www.xshots.com/upload/freaky/airspring.htm
<img src="http://www.xshots.com/upload/freaky/DDSCN4234.jpg">