I think one of the best things to do is to imitate UI controls. It's a great way to test your front-end skills and the toolkits that you're using. It's also incredibly fun.
Continuing along our previous DnD and resizing examples built in part with YUI, here's an imitation of a dialog found in Stixy, a web-based free-form collaborative and file sharing application --
There's nothing really special here ( other than how nicely the green color matches with the pink ). The DnD and resizing are basic "things" that you can build from YUI ( we're using YUI 2.3 ).
In the dialog, you can type in text. Note that both the date and time update asynchronously.
Go ahead and review the code. You'll see the full example here.