I'm still catching up on blog entries that I've been meaning to post, here are some of the tools I mentioned in my TechEd New Zealand sessions.

FXCop
FxCop is a tool that lets you know whether you code conforms to specific rules like naming guidelines, CLS compliance and much more.  Just point it to your DLL and you'll get a list of issues with your code (You can check whether you want to ignore certain errors). Download here.

ASP.NET Version Switcher
Have you ever actually tried to run ASP.NET applications that use different versions of the .NET Framework 1.0, 1.1, and Whidbey?  This is totally possible, but it can be a pain from a configuration perspective.  The issue is that IIS requires file extensions to be mapped to a specific ISAPI extension, so to have multiple virtual directories that use different versions of the framework, you would have to manually change the file mapping configuration for each virtual directory. (To do this go to IIS Manager, right click on a Virtual directory, select configuration... and change the file mappings).  You can find more information about side-by-side ASP.NET support on ASP.NET.  I mentioned in my talk Dennis Bauer's (blog hereASP.NET Version Switcher that can automatically change versions for you. Very cool and easy tool [picture]. 

Web Service Studio
If you find web services in uddi.org, xmethods.net or SalCentral (which calls itself "The Napster of Web Services"), you'll find Web Service Studio to be the easiest way to inspect the service before you actually start writing code to it. Download it here.

CLR Profiler
If you want to know how efficiently (or inefficiently) memory is being used by your application, you need the CLR profiler.  Here's the link to download it (its difficult to find on MSDN), and you can watch the .NET Show with Gregor Noriskin who walks through using the tool here

NetPing and SnippetCompiler
Scott Hanselman who always has some awesome tools up his pocket, also recently mentioned two tools by Jeff Key (blog here) NetPing and SnippetCompiler.  I haven't tried the SnippetCompiler (yet) but NetPing is sweet [picture].