Arborio rice is traditionally used to make risotto and is a short grained Italian rice that you can find in nearly every grocery store these days. It absorbs the liquid beautifully, and its starch creates a thick, creamy consistency.
Saffron is one of those magical spices that, once you use it, you will always keep some in your pantry. Traditionally used in Spanish cooking (most notably in paella), saffron has a nutty and salty quality that really elevates the flavor of risotto. Typically saffron can be pretty pricey, so try finding it in a local ethnic grocery store (I've found it in a Mexican market for next to nothing!).