Just a quick recommendation
She who must be obeyed banned me from using the typical "screw out to fit" door frame bars, which is fair enough because they do generally screw up the door frame, or require some in-situ fixings...
...so I just got one of these:
http://www.doorgym.net/Yes I know that's a horribly flashy site but the thing is pretty good - takes a few seconds to install, doesn't damage the door frame and doubles up as a deep press-up bar if you feel you need one.
I got mine for £18 including p&p from ebay.
