I've certainly dumped on both Yellowpages.com and Superpages.com and their lack of customer service before. However, according to a comscore study reported on by Mediapost, those two lead in market share of local searches.
Here is the list of the top Internet yellow pages sites and their percent market share in the 4th quarter of 2007.
Yellowpages.com Network - 20.2%
Superpages.com Network - 20.0%
Yahoo! Sites - 17.9%
Google Sites - 15.1%
Yellowbook Network - 8.6%
Yellowpages, Superpages, Yahoo and Google (not sure about Yellowbook) all offer free listings for local businesses and definitely should be tried out. I would just be cautious about doing any paid listings or pay-per-click with either Yellowpages or Superpages however.