For those of you that do ASP.NET or ASP.NET AJAX development, then the following Firebug Add-ons might be of interest to you. FireAtlas is a tool that enables you to view the PageRequestManager events, trace WebService calls, inspect Partial Updates, and view any installed application components. You can actually try out some samples pages to exercise most of the functionality of this Add-on, but I will be viewing the twitter scheduler application TwtMstr (developed by @wbm) to demonstrate some of the features in my screencast. FireCookie is another useful tool that allows you to view any cookies that are relevant for the current web page. This can be handy for an ASP.NET developer to inspect the .ASPXROLES, .ASPXAUTH, or ASP.NET_SessionId values that are common for most ASP.NET applications.