Is there a tool for making working with XML and XSLT easier

I was recently asked what is the best tool for working with XML and XSLT. Stylus Studio is an awesome tool. It will load up your xml document and will autocomplete the xpath for you. It will give you all your possibilities for each level of the xpath you're at making getting to the data needed very very easy. It makes using XPATH even fun if that is not too nerdy to admit.