I have created a minifier for Markup. It is logical that the bulk of all output is typically contained in markup opposed to requested data assets.
http://mailmarkup.org/prettydiff/markupmin.js
My code is written in JavaScript, so it would have be logically reconstructed into ASP logic, if you are using ASP. I have also updated the logic to be more precise in remove whitespace characters. I will upload the updated code as soon as I can access a personal internet connection. The update removes the single space characters that exists in output between two start tags or two end tags. Single space characters that exist before and/or after singleton tags remain in output.
My code properly ignores whitespace in ASP and PHP tags, so there will likely exist an efficiency hole not convered by my code, but easily correctly be supplying additional logic to account of syntax considerations of ASP or PHP languages.
If this code is of some assistance, but not entirely what you need I can make alterations.