I’m in the middle of comparing three popular online radio services:   Pandora, Last.FM and Slacker Radio.  All three offer you the choice of picking a favorite artist and “training” your own custom stations.  Given my recent experiences, my success rate varies among the three companies’ offerings.  In their free modes, there are limitations, which I will outline in my coverage of all three.  Look for the full comparison in a few weeks.  In the meantime, I’ll outline each one individually in separate articles, including a how-to guide to get the most out of them.