Silverlight is a amazing technology which gives you stunning look for your web applications. But the released versions dont have support to access data directly.Also you cant do cross domain web requests from a silverlight domain.
So as a solution you have to go for some other techniques for data access as well as to get data from other web sites. Hers is a small technique which access web service. You can provide a data source from a out side service local web service.
Here is a solution which uses GETISD service from a webservice and exposes a local service
This technique employs a local web service to access data from out side .Silverlight application will be communicating to this local service only.
Download sample here