Pullups are great exercise, but they do require access to a pullup bar. If you can’t get to a pullup bar, good substitutes are swings and sumo deadlift high pulls.
Crossfit typically prescibes “kipping pullups”–these involve swinging your whole body, using a lot of your core muscles to help get a better range of motion and more pullups in less time.
Crossfit Videos on Pullups
Kipping Pullup Concepts…[ wmv]
Kipping Pullups, Step 1…[wmv][mov]
ipping Pullups, Step 2…[wmv][mov]
Kipping Pullups, Step 3…[wmv][mov]
Kipping Pullups, Step 4…[wmv][mov]
Matt Murski on Pullups …[wmv][mov]
Jumping pullups are another fun variation: