Flat or Fitted, Hemp or Cotton
Already, here's a few choices for you. Flat diapers are diapers that require either tight fitting covers, good old-fashioned pins, or another type of fastner (like a Snappi(tm)) to hold them in place. There are two basic types of flat diapers -- flat (or unfolded) diapers, or "prefolds". The prefolds are already sewn approximately to size, and have extra absorbant layers in the centre, while the older style of plain flat diapers require a bit more folding. Flat diapers dry fairly quickly, have no velcro or elastic to get worn out, and fit from newborns to kids ready to start using the toilet. (And they are easy to make!)

Fitted diapers are diapers that look pretty much like disposable diapers, but are made of cloth, and 100% reusable. Fastened with either snaps or velcro, they make diapering easier, as there are no pins, and no folding required. They do take longer to dry, and (usually) required the purchase of a few difference sizes, as the baby grows. ecomum has chosen two brands of fitted diapers to distribute, for their good value, effectiveness, and ease of use: The Indisposables Diaper, and the Always Fit Diaper from Diapering Decisions.