It was also pretty cool how they included the original versions of all the built-in PIM apps as sample code in their SDK. It meant that there was a huge amount

It was also pretty cool how they included the original versions of all the built-in PIM apps as sample code in their SDK. It meant that there was a huge amount of "Datebook+" or "Memos+" type apps that was just the built-in app plus some handy features the developer wanted themselves, without the developer having to re-invent the wheel (culminating in some fantastic advanced apps like Datebk4)