Image map 'Text' images can be changed to allow help for the reader, again by manipulating the properties of objects, such as the 'src' of an image. Calculate BMI Functions can be used to process information directly on the web page, without reference to the web server. Arithmetic More function examples, along with use of radio buttons. Color explorer This one is just fun for me and an example of heavy radio button use. I think it can be simplified.
Image play The use of arrays in javascript can allow slide shows, for example.
This page Even this intro page has a bit of javascript in it. Date and Time Javascript comes with some useful built-in object besides the web pages themselves. Web pages can create web pages without calling a server. Virtual pieces However, useful javascript code can be stored on the server for use in many web pages, e.g., a common 'look and feel'. Javascript can communicate with java applets, something that I think ought to be useful.