For those living in the UK, its inevitable having to call various customer service telephone numbers. And if that number begins with a 0870, you can get charged quite a bit depending on the service you are calling and how long you spend waiting in the queue.
Recently, i discovered website called - saynoto0870. It can be used to lookup alternate numbers using either phone number or the company name. For example, i used it to look up a alternate 0800 number for Sky. There's a helpful forum too. To make things easier, someone has put together a Firefox search plugin too.
And no, i am not affiliated with the website. I am just a satisfied user :)