The way I look at it is, as long as it doesn't cost anything to get listed on the yellowpage directory websites it's a good idea to be there. I've got my business listed in the superpages and now, thanks to your post I'm going to check out the others you mentioned. As far as actual results from my listing in the superpages, I'm not really sure I've ever had someone contact me because they saw my business listed there. However, it's not that easy to know exactly how and where someone was directed to find your contact information. If it's free, go for it.
