I'm basically a back end database kind of guy, but over the past years have been doing more front end web stuff. Asp.Net has been a huge help for me, and now with Visual Studio 2008 and the JavaScript debugging capabilities, I'm finding doing web stuff is just not so bad. Many of you know I've written several MSDN articles and one of them was over a year ago on how to add Ajax to my Membership solution (back then it was called Atlas). The article is still out there though now a little out dated. In it, I extensively use Alessandro's code he posted on his blog. My point here is Alessandro keeps up with this stuff, and as it turns out, he wrote an excellent book that's been helping me out.
I enthusiastically recommend it to anyone trying to incorporate Ajax into their asp.net applications. It's not only got a great introduction, but also goes into lots of useful details for day to day programming.
 Amazon.com: ASP.NET AJAX in Action |