Due to browser's prohibition on cross domain XMLHTTP call, all AJAX websites must have server side proxy to fetch content from external domain like Flickr or Digg. From client side javascript code, an XMLHTTP call goes to the server side proxy hosted on the same domain and then the proxy downloads...
ASP.NET 2.0 has many secrets, when revealed, can give you big performance and scalability boost. For instance, there are secret bottlenecks in Membership and Profile provider which can be solved easily to make authentication and authorization faster. Furthermore, ASP.NET Http pipeline can be tweaked...