Dave Ward from encosia.com has three copies of Advanced ASP.NET AJAX Server Controls For .NET Framework 3.5 to give away, but there's a catch. In order to get a shot at getting one of the books, you must participate in an open source project that he has started on Codeplex.

The project is an ASP.NET AJAX Server control that will validate username availability on the server and show an inline confirmation as to the availability.

You can find the project here on Codeplex and get more information about the giveaway and ways to participate here on encosia.com.

BTW, if you're interested in ASP.NET AJAX development, subscribe to encosia.com via an RSS reader or visit the site sometimes, he's got great tips there.