Apple offers industry leading Accessibility options for the iPhone, iPod touch, and iPad, but in order for them to be useful, the options themselves have to be accessible, don't they? Well, they are! At least when you set them up! Once done, a simple triple-click of the Home button will either toggle on your preferred option, or more flexibly still, give you the ability to choose from one of several options.
If you choose to be asked, every time you triple-click Home, you'll get the Accessibility options.