Instant username availability validation is a feature a lot of my clients have been requesting lately. Basically it is a function that checks to see if a username or email address is available instantly, as it is being typed. My internet life matured in a time when JavaScript was the devil. I have avoided using it in development for as long as I remember. I still heavily avoid it because of how fickle some of the browsers handle it, and because elegance is time consuming. Most sites that reconfigure themselves with AJAX fail to execute properly -- if you are going to use JavaScript, take the time and do it right. However, I am also aware of how well some of the frameworks out there have overcome the weaknesses of cross browser compatibility. I have included a link that has all of the programming details outlined for you to use. Any thoughts are welcome! http://blog.dagoosh.com/post/2009/03/30/jquery-aspnet-live-validation.aspx