Check out the Native Extensions for Microsoft Silverlight - a set of libraries for Silverlight developers that allow you to access some really cool features of Windows 7 from your Silverlight app.
Source: MSDN
While Silverlight 4 supports accessing COM automation components from elevated trust OOB applications, many Windows platform features are currently not available through COM automation. This makes them inaccessible to such Silverlight OOB apps. Native Extensions for Microsoft Silverlight(NESL) is an effort to incrementally build a library of components that expose select Windows 7 features through COM automation, making them easily available to Silverlight 4 OOB applications running with elevated trust.