Calling the phone number 800-CALL-411 in the USA provides a free phone directory search service by Microsoft.

It also provides a few other services. One I just noticed is "cheap gas".
"Gas" in the US refers to gasoline (i.e. petrol).
If you give it a location, it will give you a list of some gas stations with lower gas prices. It gives the name and location of the station and the price for regular gasoline.

Web service
http://polttoaine.net/
has been provided in Finland – several years.