I have the same question here as I did in the Yahoo API forum. How much does it cost to use MSN's search API commerically?
There API is a web services kind of thing. Not to sure how well it works with other development tools besides Visual Studio because I see there web services API is in the .asmx extension and that is a Microsoft extension for Web Services and it is SOAP and not REST.
Here's a handy dandy SOAP client (PHP) as well as some discussion.. MSN API SOAP via PHP To see it in action: MSN API Search Client in action This guy has done a nice job of it actually, and for the coders among you, should answer all questions (but do watch pre PHP 5 SOAP bugs folks).. Cheers, JL