Masoor dal (also called a red lentil) is the fastest cooking lentil, no soaking required. The backbones of this dal are ridiculously cheap but will comfort your guests like only a healthy stew can.
Note: Do not skip the tempering step! This technique is called a "tadka," and is commonly used in Indian cooking (http://en.wikipedia.org...). The whole spices are heated up in fat (oil or ghee) and poured over the lentils before serving, infusing the whole dish with flavor. It may sound totally decadent to pour hot butter onto a dish however there's not much fat in the initial lentil mixture, so don't skimp!