I'm currently "Greasing the Groove" with pull-ups, as made popular by Pavel Tsatsouline.
I tested my max pull-ups then took that number and divided it in half. Then I perform a set of that number of pull-ups through out the day, every day. The key is never going to failure. I might do 10 or 15 sets during the day.
http://breakingmuscle.com/strength-c...t-work-for-you
We shall see. I'm only doing it because I can't get to the gym for a few weeks but do have a pull-up bar.