Never Gymless is the title of a book by Ross Enamait.  This book is focused mainly on body weight training, such as push-ups, pull-ups, rope climbing and other bodyweight endeavors.  There is a lot more though.  Tons of info is presented on program design, exercise variations, and even diet management.  By the way, the diet section is right on.  Another thing I like about this book, it is no frills and all substance.  There isn't 30 pages of BS ad copy hyping some secrets book or whatever.  I guess some people like that stuff but I like gettin right down to business.  There is literally enough info on bodyweight training in this book to keep you busy and fit for the rest of your life.  There really is no excuse such as I can't afford weights or I can't afford a gym membership.  The good news is you don't need one.  I would be willing to bet that if you you trained in this way you would be more fit and you would have a better physique (that is all a lot of people who exercise care about anyway) than 90% of people training at a commercial gym.  Of course it is hard work so some people won't like it but WTF?  you get what you work for. 
Ross has a great website where he has a lot of training videos and excellent articles in addition to the stuff he has for sale.  Check it out at www.rosstraining.com

One of the things this book turned me on to is rope climbing.  I just set up a station in my back yard.  I got a 30 ft 1.5" diameter manila rope from www.mcmaster.com  (These guys sell anything and everything and they ship quick too).   Rope climbing makes chins and pull-ups seem like a picnic by comparison. Anyway superset some rope climb sprints (no legs if you want to make it tough) with some push-ups.  Your upper body will get a complete workout push-pull style.  Quick and to the point.

There is an important caveat I must insert.  You had better know what you are doing when rope climbing.  It has to be safe otherwise you'll get hurt...bad.  Make absolutely certain your knots are tight and will hold... ditto for whatever it is tied to.  Also use quality rope and inspect it regularly.  In my set up I am tied to a thick branch with a secure knot.  Then I am also tied to a branch about 3 feet below as well.  I wrapped it 3x and knotted that again.  Now two knots or two branches have to go before I fall.  My climbing distance is about 20 feet so I am not going nuts there either.  Remember to be safe.

If you do this right it is safe but if you do it wrong you'll end up like so many idiots who get drunk and fall out of tree stands while deer hunting. 

Till next time... Train smart.

Scott