I do most of my web development work in ASP.NET. I've mastered ASP.NET 1.1 and ASP.NET 2.0. I've read many books on ASP.NET 2.0 and use most of its features. I have upgraded a large web application to ASP.NET 2.0 and made many improvements using AJAX. I use Visual Studio 2008. I can program in C# or VB.NET and spend equal amounts of time using both languages. Some of the more sophisticated ASP.NET work I do includes web services that return JSON data and web request handlers.
Currently I create new web applications using ASP.NET 4.0 and Visual Studio 2010. I use SubSonic for object-relational mapping.
There are a few demonstration ASP.NET pages on this site that use the YouTube API. These pages demonstrate how ASP.NET can make web requests and process the XML that is returned. See my YouTube Favorites Backup page for an example.
Microsoft now officially supports jQuery for ASP.NET web development. They have added IntelliSense for jQuery to Visual Studio 2008. I make extensive use of jQuery for my AJAX demonstrations and in all my other projects.
Most of my ASP.NET projects have used SQL Server for the database back end but it is possible to use MySQL to save money and I am familiar with how to use MySQL with ASP.NET. For example, the web hosting company for this web site only provides a MySQL database so I write my ASP.NET pages to access MySQL.