I am thinking for a new approach to make small webapps using XML. Here the the procedure to make it.
First of all design a DataBbase for Application. This database is the soul of your application. This database contain all the necessary data and values. Now when a user requests to this webapp, the server will execute a server side script and will return a xml file. The returned xml file is actually a xml converted database. In otherwords, server will return whole the database as xml file. Now the client machine has the whole database as one xml file. At the same time we can use Ajax push technique, so that any change in the database on the server will be reflected into client side xml file, also any change in client side xml file will be ajax pushed into server side database. By this mechanism we can have a syncronised databases in server and client side. Now a client side XSLT will render the client side xml database file so that user can view the application and intract.