I am just about to release some Business Listing search software. It is called Topicala Business (http://www.topicala.com/business/). If you are the owner of a UK business you have to opportunity to claim your listing and add a description of your line of business, a list of services you offer and contact information such as a URL, Address and telephone numbers for free.
Topicala Business is Unique in that it also searches the web for you so that you can find out what your customers and competitors are saying about your business.
If you know your company number you can visit your page by typing in the follow www.topicala.com/business/{companyNumber}. Alternatively, you can perform search on the business name from either the main page (http://www.topicala.com/business/ ) or by using a direct query string request. For example, Topicala Ltd can be found using the URL http://www.topicala.com/business/topicala or http://www.topicala.com/business/06512461
The information is pulled from Companies House (http://www.companies-house.gov.uk) and is licenced under Crown Copyright.
I am still in the process of loading business information but there are already 169106 companies listed. Granted, only the registered addresses are available. But as more companies use the site, the more information that will be available.
Anyway, give it a try, claim your business and edit your listings so that potential customers can find your business. All the Business Listings are submitted to Google, so you can promote your listings how you like to give your company information a boost on the search engines.
I will be adding more features as I go, but I am very interested in any comments you have or any features you would like to see.