Pocket diapers are, in my opinion, the biggest innovation in cloth diapering in the last 20 years. Pocket diapers will be responsible for a major resurgence in using cloth diapers as more and more people discover them! They consist of an outer layer of waterproof material and an inner layer of microfleece or suedecloth, which keeps baby feeling dry and helps prevent diaper rash. In between those layers you stuff whatever material you wish, to customize the level of absorbency you need.
They're so easy to use, and easy to wash! AND they're generally adorable. It is more expensive to use pocket diapers exclusively, as compared to other cloth diaper systems, so some people use a combination of systems, reserving their pocket diapers for going out, or for daddy, grandparents, babysitters, etc. But even using all pocket diapers, you still come out about even money-wise as compared to the cheapest disposable diapers. And that's just for one child - if you use these cloth diapers for more than one child, you will save LOTS of money!