kellysearch , yell.com
Matt, like pest control has said, Kellysearch. I'd been listed with them for ages now - don't get as many enquiries through them as I used to but I think their serps have dropped a bit this year. Still a great place to be listed - For Free.
yell.com? Those that know me know my thoughts about Yell group of companies. I had an extremely bad experience with them to which they weren't interested in sorting out, and they still try and get my business - but not a hope in hell in getting another penny from me. They're great (especially the book) when everything run's fine, but from my experience they're dire if things go wrong or you have an issue.