For those of you who spend a lot of time dealing with XML data, you might be interested in this add-in for Visual Studio:  IronXSLT .  Written by XML MVP Oleg Tkachenko, IronXSLT aims to provide complete integration of XSLT into the VS08 environment.  Features listed on the website for version 0.1 include:

XSLT Library Project (Visual Studio project type for compiling XSLT into DLL)

XSLT Refactorings

Multiple XSLT engines

XSLT Profiler

Extensive library of XSLT code snippets

XPath Intellisense

Visual XSLT builder

XSLT2XLinq and XLinq2XSLT converters

If any of you are active XSLT users, I'd be interested in feedback from you on what you think.  The bits that sound really interesting to me are the XSLT Library Project, Intellisense, the Profiler and the Visual Builder.  Once upon a time (1999?), I spent a *lot* of time in XSLT, and the tools were pretty sparse back then.  It looks like between the XML features in VS08, great tools like XML Spy and IronXSLT, that gap has been pretty much closed.  I'm downloading it right now...