Bodyweight Exercises.

[AdamGB]

I normally give the plank out to newbies. Starts to teach the motor neuron's in the core to activate. The complete beginning of any muscular development is actually teaching the nervous system to be able to fire up the muscle fibres... only once you've done that will the muscles start to develop as you increase the stress placed on them.

Anybody who has been doing some serious press up training, with correct technique will have essentially been activating the core in the same way anyway.

Oh and Clubber, to answer your question: You're a plank!