please look here. On the top right side of the page there is a box that contains multiple content that can be switched by clicking on the buttons name "Most commented" "Most read" I think its ajax based or its html and css combination thanks
I think javascript alone can do that. Though it can also be done with AJAX. I had myself written a JS for it at javascript.biologyformhtcet.com/display_tabbed_items.html(Copy-paste URL into browser) It may little bit of cleaning though.
Should be possible with JS and CSS. Set the onclick function to JS which alters the visible state. Just google for a javascript css tutorial and it should be covered.