I too rarely boil. I asked this question myself a while back and did a little research. Basically, 5 minute boil kills bacteria and whatnot, 15 minutes boils out chlorine and other minerals out of tap water. IMHO, mineral-less water is not so good for yeast.
Personal experience, liquid courage and the ability to sacrifice a precious batch of delicately harvested yeast one day wanted to see how it would turn out if I didn't boil. Tossed water in microwave for 2-3 minutes, cooled and added yeast. Did this 4 batches in a row and never had any problems, actually seemed like my yeast took off quicker.
If boiling makes you happy, by all means do it. My friend uses just warm tap water and he has had zero problems.