<p>Does anyone know a good tool that can be run on a page (for asp.net, for example) to help to minimize the footprint size of the page?</p>

<p>The page will have typical items: HTML, Javascript, etc.</p>

<p>I've heard of Javascript crunchers in the past, that will make the size of the code as compact as possible (and obfuscate it, I suppose).</p>

<p>The goal is to help optimize the page size (make it as small as possible for speed, without changing anything).</p>

<p>Is this possible?</p>

Well, its not a automatic cleaner-upper, but I like
YSlow
for optimizing pages.  And the
YUI Compressor
can minify your javascript.
If you're really interested in javascript, the keyword is "minify".
Also, look at this question just posted:
HTML and stuff
Hope that helps!