More on heuristics
The cognitive psychology Thinker has a few great minitutorials that give examples illustrating some of the most common heuristics.
From the site overview:
A number of factors can affect how we go about making decisions, but it is unusual for us to make a decision completely objectively and rationally; rather we usually bring biases from our prior beliefs or experiences into the situation. As a result, we often use "rules of thumb," or heuristics, to help us. These heuristics allow us to have an idea about how to weigh our options, even though they might sometimes lead us astray. Likewise, sometimes the way our options are worded, or "framed," may lead us to think differently than we might otherwise. Finally, we often allow prior experience or outcomes to guide our approach to a decision, even though, again, that approach may not be the best way to go.