We worked a lot in the past months on NCryptoki to find the best way to integrate PKCS#11 tokens in a web page (aspx, php, jsp, etc.). Till now we proposed the Java Applet approach based on JCryptoki and JQuery script to embedded the JCryptoki classes in the web page. Such a Java approach works as expected by has some not nice-to-have security issues that: 1) give a bad user experience; 2) are higly dependent on the JRE installed on the client side. So we searched for a better way. We ported the entire NCryptoki package to Silverlight 5 and we have created a Silverlight user control that exports the NCryptoki classes to the JavaScript world. This approach seems more robust and very nice respect to the user exeprience and doesn't give strong security issues.
You can see a demo (PKCS#11 dump) on my blog: http://www.ugochirico.com/post/2013/10/18/Call-PKCS11-from-Silverlight.aspx