"Well, real estate is always good, as far as I'm concerned."
-Donald Trump
I'd have to agree with "The Donald" on this one. Real estate, if anything, is valuable. Especially when your dealing with the UI in your software. One of my favorite components of the AJAX Control Toolkit is the ModalPopupExtender control. There's a quick & dirty explanation and demo
[HERE] of this control on the www.asp.net site but I don't feel like the posting does justice to the true functionality of the control.
In this posting I'll shjow how to use the modal popup extender to increase the amount of real estate available on the page, by hooking up a selectable GridView in a modal popop with a form entry on the main page. My goals are to show how the control can extend beyond simple display capabilities and can be used to hook up data between modal form and page form.
You can download the demo projet i whipped up from my Windows Live SkyDrive (Try it! it's free] here:
As you can see below, some form entry items can be very simple in appearance, but complex in the way they are chosen by the user. For example, this user needs to enter a specific product into the form.

Since nobody has a real time database in their head, they must chose. We use the modal popup extender to pop up a product selection form that allow the user to see a sortable list of products along with associated inventory and pricing. All good information that we wouldn't want to waste screen real estate on in our main page. The popup looks as follows.
After a user selects the product, we leverage the ASP.net AJAX cleint side control accessors ($get('contorlname')) to grab the selected product and push it through the DOM into the main page.
That's it. Pretty cake example but i think alot of people overlook this capability.