The scenario is basically - if you had a camera, lens, (with batteries and memory card - basically everything you need to take photos, as well as the computer side sorted) what three accessories, listed in order, would you absolutely not be able to do without? Feel free to elaborate on your choices!
This is not about lenses or bodies - just accessory items that enable your system to really get great results.
For me it would have to be:
1) Circular polariser
3) Off camera cord or (I wish!) a set of pocket wizards.