I've been playing around with ASP.NET AJAX ("Atlas") a bit recently. It's got some pretty cool stuff if you're into web development, and ASP.NET in particular. The documentation isn't that great, so it's hard to see exactly what all it can do, but there's definitely a lot of potential in there. I'm sure I'll post more about it once I've learned more.
But what it can do to a databound GridView control is pretty amazing. You add one ScriptManager control to the top of the page, set a property on it, and then wrap your GridView inside of an UpdatePanel, and then magically the old non-AJAX GridView becomes AJAX-enabled and doesn't require page postbacks to update. You can page through data, sort, and even get live updates, insertions, and deletes, all without page reloads or any code at all.