There's a product I've been using long before I had a baby, and long after, and it will be one of the first things I stock up with before my due date. It's Bennetts Baby Bum Crème, aka one of the best nappy rash protectors I've come across, and certainly the best anti-chafe cream I've ever used for long-distance running. In fact, you'll never find me at a marathon without a small tub of Bennetts, and it's the only thing that has ever worked to prevent chafing (particularly on my bra lines).
Bennetts Bum Crème has just changed their formulation, and it now contains soothing D-Panthenol, to take it from great to even greater. It's formulated in a water-repellent base, and forms an effective barrier between a wet nappy and baby's skin.
Bennetts Baby Bum Crème is available from chemists, supermarkets and baby stores, along with their other products that include bath and massage drops, soap, aqueous cream and saline drops. The cream comes in various sizes, in either tub or tube formats.