I'm not sure how I missed this but we've shipped a ScriptReferenceProfiler control on CodePlex specifically to assist with the new ASP.NET AJAX script combination feature in .NET Fx 3.5 Service Pack 1. In case you're not familiar with the script combination feature, you can now ask ASP.NET AJAX to "aggregate" the scripts required for your page into a single request. This is done with the new <CompositeScript> element on the <asp:ScriptManager> control. But how to know what scripts are required on your page?
Enter the <asp:ScriptReferenceProfiler>. Drop one of these on your page and it will render the full list of <asp:ScriptManager> scripts required for the page to function. You can then take this list and paste it into the <CompositeScript> element of the <asp:ScriptManager> control. Not only does this ensure you have the minimal set of scripts required to service your page, it also forces them to be combined on the server and served up in a single request via the ScriptResources.axd handler.