As I will hold an XML Workshop focused on XSD, XPath and XSL/T for a large group of employees of a customer tomorrow, I have tried many things with XSL/T during the last few days. The annoying thing with XLS/T is not only, that it is hard to read when getting more and more complex (remember my last posting), but you even don't have IntelliSense in Visual Studio .NET.
Fortunately there is a very easy possibility for getting IntelliSense support (look at the article from Aron Skonnard in the January Web Q&A of MSDN Magazine http://msdn.microsoft.com/msdnmag/issues/04/01/XMLFiles/), because Visual Studio .NET has a built-in generic IntelliSense mechanism based on XML Schema for tag oriented languages like HTML, XML, XSD and so forth.
Thus, all you need, is a schema for XSL/T (which is not easy to find, because the W3C does not have created one). Just navigate to http://www.fesersoft.com/dotNet/ and look for XSL on the page. It seems to be a nearly complete schema for XSL/T. You need to download the ZIP archive and put the xslt.xsd file (I have renamed it to xsltschema.xsd) into the schema directory of Visual Studio .NET which is located in the Common7\Packages\schemas\xml directory of the Visual Studio .NET program files folder. After you have copied the file into this directory, create a new XSL/T document and try it out.