Originally from http://www.umbraco.org/frontpage/documentation/articles/sampleofthemonth.aspx
When developing using xsl, the language sometimes falls short or its difficult and time consuming to accomplish what is easily done in other programming languages.
Answering a question in the umbraco mailing list, revealed that it wasn't common knowledge that you could extend xsl with inline code of your favorite programming language, but it is in fact very easy to do so.
You can use different programming languages, a complete list and further information can be found at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconXSLTStylesheetScriptingUsingMsxslscript.asp
Author: Kasper Bumbech Andersen