welovelocal.com is essentially the Yellow Pages written by your friends. It provides a full directory of UK businesses (currently London only but launching across the UK shortly) and contextualises the reviews, and a network of friends around you.

The SOAP API allows you to query the sites data stores with different functions that let you get businesses by a search term, get their reviews and search the businesses based on a category and a search term. The reference page includes the input and output values of the API as well as some sample PHP code to show you how to make the request (using the SOAP functionality in PHP5).